Yes it is hard to believe, but if it is true that he is making $100,000 per month, then he was right not to sell it, wasn't he? The site still has a good traffic and a lot of potential.
50,000 naked men/day is about 1,500,000 naked men per month, so $100,000 would be less than 7 cents per naked man. As this is highly targeted traffic, that does not sound completely unreasonable.
Keep in mind that 50k uniques/day doesn't translate into 30x50k uniques/months. There are probably some repeat visitors. Otherwise the world would at some point run of naked men.
Still, it's a non-trivial amount of highly targeted traffic.