​I see at least two problems with this case study.

First, what sort of sampling bias is introduced by studying only men who are willing to view such materials? It seems highly implausible to me that this effect is zero.

Second, if true, this theory should generalize to other cases of people who express an exceptionally strong opposition towards some low-status/disreputable behavior that can be practiced covertly, or some low-status beliefs that can be held in secret. Yet it's hard for me to think of any analogous examples that would be the subject of either folk theories or scientific studies.

In fact, this generalization would lead to the conclusion that respectable high-status activists who crusade against various behaviors and attitudes that are nowadays considered disreputable, evil, dangerous, etc., should be suspected that they do it because they themselves engage in such behaviors (or hold such attitudes) covertly. The funny thing is, in places and social circles where homophobia is considered disreputable, this should clearly apply to campaigners against homophobia!