Again, I disagree. Cults can't form around anything. They can only form around issues that would make them social or intellectual outcasts. And in a world in which there were poorly hidden aliens, too many intelligent people would be of the opinion that there are poorly hidden aliens, and no such cult could arise.

But the more important point is... IF I start to think that there are poorly hidden aliens, that could be due to one of two reasons: either because I have reasonable evidence for their existence, or because I'm being influenced by some sort of bias.

The existence of cults around the issue shows that those biases exist and are reasonably common, and thus are a more likely reason for my belief than the alternative of actual aliens.