The correlation is interesting, but it hasn't convinced me that "EBV is the Answer!" It might just indicate that some PWME have worse symptoms due to some form of viral infection.
I too believe PWME have varying symptoms due to some form of viral infection. Especially based on level of infection, number of infections, type of infection, and locality of infection.
If you consider the Occam's Razor principle, in that “the simplest solution is almost always the best,” then EBV would be a very logical #1 theory. I think there's a reason why EBV is been involved in so many CFS studies since like the 1980's up to now.