I can honestly say they decide what to ban on a coin flip.
Both my series are very much mature rated and one of them got banned because it features a half naked woman. So far so good, their mature tag isn't worth shit, but ok. The thing is, my other series has been up on their site for nearly three months now. It has explicit gore, nudity and a straight up sex scene.
Wouldn't recommend putting spicy stuff up there if I were held at gunpoint.