Scientists are extreme specialists.
Given a little effort (and some expert advice from necessarily more than one source) it is probably possible to stuff the Albert Hall–or many another iconic auditorium–up to the chandeliers with scientists, most of whom, if randomly distributed, would be unable to have a meaningful scientific discussion with any other scientist within shouting distance.
My point is, if scientists are so specialized that they can barely talk to each other, how could they rationally engage in monolithic international conspiracies?
But I forget myself.
A good conspiracy theory requires neither logic, motive or evidence.
My bad for getting logical.