If someone is ready to pay bitcoins for porn then it might be a good fit together since bitcoin offers a good privacy level, I remember po--.com used to accept bitcoin but I think they stopped using it after they had processing issues or due to low demand.
Now lot people prefer to pay with bitcoin as it is anonymous to certain extent. Even now and then the price difference will give additional profit if payment is made through bitcoin.
It's true that payments with Bitcoin can give more security, anonymity and safety to porn users but police usually find such people in other ways, either through online database of users in porn site or through IP's addresses and through some other ways like finding porn content on their computers.