It doesn't matter what the political motivation for questioning is. Specifically, it doesn't affect whether any accusation is plausible or true, or to what extent.

Sure, accusation isn't evidence, but to disqualify a theory immediately or primarily because of what kind of people were its first or are its major proponents is the guilt by association fallacy, that you were saying is bad only one paragraph earlier.

You should really decide whether you want to criticize people for using fallacies, or whether you want to use them yourself. Or, again, at least put more space between the two.