This case is actually pretty simple. The caption said 11 naked show photographs. Underwear is not considered naked. If he held a towel up over himself so you couldn't see if he was naked or not, that would probably slide, but this is cut and dry.
I have seen others mention that OnlyFans tells them no if it's as you said just implying, but this is clear. Also if OnlyFans says no you can just report it to the credit card company and you have a 100% chance of getting the money back. The downside is that OnlyFans will likely close your account.