My guess is that most YEC would not claim a massive world-wide conspiracy, but rather a massive bias towards naturalism.
I have to say that I haven't paid much attention to what YEC's say since I strongly disagree with them. But yes, I don't think that it's accurate to call them conspiracy theorists and I certainly wouldn't call them that myself.
Speaking about scientists, I agree that science's commitment to ("bias" towards) methodological naturalism does kind of rule out special divine revelations as a source of scientific knowledge. If basically the only justification for YEC comes from special revelations supposedly contained in scripture, then YEC isn't going to find any role in science.
This doesn't render YEC impossible though, just unscientific. The idea (very popular among atheists) that the boundaries of reality are coextensive with the limits of science, is metaphysical naturalism. I think that just by its nature metaphysical naturalism isn't justifiable.
The fact that most scientists are not YEC can be explained by appealing to this bias.
Sort of. Even if we reject science's methodological naturalism, there's no guarantee that scientists would all be YEC's. It isn't the only alternative. There's may different ways that things could be, limited only by our imagination. Some scenarios might involve creator gods, such as God being responsible for the "big bang". Some might not envision a creator god at all. For example ancient Indian tradition imagined an infinite past without an origin. Since they believed in reincarnation, that meant that all of us, while being unique new phenomenal personas, are populated by selves (the unseen seer) that are already infinitely old. Each of us has already seen it all, we've all been gods, men, insects and hell demons in past lives, moving up and down the scale as our karma dictates, forever without a beginning or an end. Sort of the antithesis of YEC.