I just looked at the screenies on the store page. Take note: a drawer full of blatant porn. Also take note: rated T for Teen.

I don't think that's blatant porn, more like... "early photography days erotic soft-core".

Artistic early nude photographs are hardly blatant porn as there is no penetration or close up of female genitalia.

Nudity as such doesn't automatically require 18+ age limit. The game isn't pornographic, but it's an horror adventure with some suggestive themes, like it is said in the rating.

When I found the drawer with the aforementioned pictures (which are about the only kind of nuditiy you're gonna see in the whole game) I actually figured it was to show that the owner was in fact interested in the opposite sex...
Made me chuckle a little, since there is definitely some kind of bromance going on there, and I thought the dev just wanted to water it down a little. So at least it's not completely arbitrary.