Their evidence, which is flimsy, is that since they said that the microbe was suspected to be the cause of the disease even though they couldn't see anything in the blood before they did electron microscopy, the presence of something suspicious in the blood which was found later through electron microscopy couldn't be the basis for the initial suspicion. This is the equivalent as saying, "the President's staff was suspected of colluding with Russia" and then later finding recorded calls between staff members and Russian state officials. The recordings couldn't form the basis of the initial suspicion, since they were discovered after and as a result of that suspicion.
