Basically my problem with the Coyne take on the lack of empathy for ME patients is that it doesn´t really explain why, for example, my mother did not seem to have much sympathy for me feeling awful all the time a year ago, when I showed sympathy when she got a cold. I guess Coyne would say that it´s because I have experienced a cold, whereas she hasn´t experienced ME. But I don´t think this is a sufficient explanation for this phenomenon, since I am pretty sure I would feel sympathy for her if she had, for example, a kidney stone, although I have no idea what that experience is like. I noticed that my mother was quite sympathetic to my condition for the first couple of weeks I was ill, and then became less so, despite the fact that my symptoms had actually worsened. I think this is because we have evolved to show sympathy for and take care of people who have acute illnesses (since they might get better soon and therefore once again contribute to the group), but not those who have chronic illnesses (since there isn´t much chance they will get better soon and therefore will continue to be a drain on the group´s resources). Looking at it this way helped me to accept this lack of sympathy, since it helped to depersonalize it. Also, when someone does show me some sympathy, I see them as offering it in spite of themselves (or in spite of their genetic make up) and I am therefore less likely to take it for granted.
Of course, if you aren´t satisfied by biological explanations then you probably won´t think that the above is a sufficient explanation of the phenomenon either.