DeFreitas did find big differential results under blinded conditions in her own studies, as the document explains, but under external blinding, that fell through. So in every respect, XMRV is deja vu all over again.
What could perhaps be different this time - and should be - is that a full and proper explanation of why this happens is needed, and steps to ensure it can be dealt with and prevented in future. Robin Weiss' own similar problematic findings, which he himself has since dismissed, are another example of a similar case that remains unexplained.
There are only three types of explanations I can see for this pattern, though I may well have missed something:
1. Some type of systematic contamination issue affecting patient samples more often than controls. Extra handling of patient samples is a possible explanation, and it's the front-runner, but it isn't necessarily that, and it should not be considered 'case closed' on that question. Whatever it is, it is extremely non-obvious, or it wouldn't keep happening. More research is needed to determine exactly how this can happen so that scientific protocols can control for this in the future.
2. Some genuine non-obvious aspect of the experiments which enabled success in the positive studies but was not carried out in the externally-blinded studies. Again this would have to be extremely non-obvious, and suggestions like the significance of the heparin used in the tubes are just guesses to try to figure out what this could be. There could be something the original researchers did which was essential to success but they didn't and don't know what that was.
Again: more research is needed in order to distinguish between option 1 and option 2. Until that question is definitively answered, the mystery remains. It is unscientific to assume the hypothesis of 1 without evidence or proof. Proofs of concept are useful (this is what Singh did, I believe, and it's a major advance), but it needs to be shown how they really did apply in the actual studies. Until that happens, reasonable doubts will remain that there may be something in option 2.
3. The externally blinded studies were "gamed" by some unknown third party, either directly involved in the blinding itself or an agent from outside. This is, of course, the taboo subject of conspiracy theory. I'd like to point out that there are many theoretical possibilities for such a third party. An agent of the government in some grand conspiracy is perhaps the least likely. Other options for the third party include a shadowy private group interfering with the samples by espionage, a foreign government or rogue nation state doing so (possibly involving biological warfare), and if you want to step out there, aliens could be doing it to suppress us or to manipulate our genetic evolution for reasons unknown. Of course, all the theoretical possibilities in this class of explanations are considered utter nonsense, to be automatically dismissed as insanity, by all reasonable and respected commentators. I guess I'm not quite in that category, and a little insane therefore, because I don't see why such possibilities are all utterly impossible. I certainly don't give them a high probability, but unfashionable though it is to say it, nevertheless it's true that the probability of such matters is never, in fact, zero. However, it's significant to note that in any such explanations, it's worth being aware that if they are true, then by definition, we are almost certainly never going to be able to find out or prove them...so it's kind of academic...
Whatever the explanations for the DeFreitas and Mikovits findings, one other point seems most important. These two examples can be considered to be "false alarms", but they both illustrate that widespread laboratory contamination with unknown accidentally man-made retroviruses, that infect human cells, at least, is an undisputed fact. It's also undisputed that such contaminants are potential biohazards. And such contaminants and potential human pathogens have been created in the laboratory, unknown and by accident, and spread around the world, for many decades - and more are still being created. Furthermore, it is known in animals that such retroviruses have 'successfully' (accidentally) been transmitted between species in vaccines.
So regardless of whether these two "false alarms" were harmless retroviruses, there is almost a guarantee that there are many more such contaminants in existence, undetected thus far, and indeed there is almost a guarantee that, sooner or later, one of these will be pathogenic in humans, if indeed this has not already happened. Furthermore it is at the very least entirely plausible that such unknown viruses may explain currently-mysterious illnesses, outbreaks, and rising levels of medical conditions. Because this class of viruses do typically cause neuro-immune complications, they are a prime candidate to explain the H1N1-induce narcolepsy reported in 10 countries, gulf war illness, the unexplained rapidly rising levels of allergies and immune deficiencies in western countries in the last century, other alleged and disputed cases of vaccine damage, perhaps even the emergence of HIV/AIDS, and of course the unexplained neuro-immune illnesses ME and autism. In the case of ME, looking at the outbreak history from 1934 and 1955 in hospitals, affecting medical staff only, in precisely the areas and times where novel polio vaccines were being trialled, they really fit very well as an explanation of otherwise extremely puzzling epidemiology...and one can't avoid the fact that there are government files from the latter period (the 1950s in the UK) dealing with vaccinations and specifically the 'polio vaccine crisis', which are still official secrets to this day.
So whatever the case regarding DeFreitas and Mikovits, this is still a massive, massive issue and a highly plausible explanation for the epidemiology of medical conditions that are not yet understood. It is not in the public consciousness at all, and that's fairly understandable, but that does raise questions about the control of public information. And while it would be most unwise to conclude from all of this that this is definitely the answer, and this is clearly the explanation - that really would be unwise, because it really might not be - anyone who examines the evidence is bound to find this broad possibility compelling, frightening, and more than worthy of considerable further investigation.
And anyone who does investigate it and write about it is only the more intrigued, suspicious and disturbed when they encounter all the brick walls and the immediate, angry, vicious knee-jerk denial of authorities working in and around this area, as well as the associated media blackout. Those factors, more than any other, are what generate and maintain the conspiracy theories, which is really to say that this whole area of inquiry is effectively defined and marginalised as a conspiracy theory precisely by that official denial that this is a possibility worth considering. But it's important to remember that this situation is not necessarily evidence of 'conspiracy',and can equally well be explained as the behaviour of an insular and paranoid elite which does not trust the public with difficult information and is afraid to explore - at least publicly - these very difficult questions. Although whether that is merely a question of semantics and how one understands the word 'conspiracy' is another rather complicated question...