While it is a sin to 'fantasize' about such things I do not agree that one should be incarcerated unless there is a threat to society.
There is a lot of sickness in the movies today, murder, rape, violence, hatred, adultery, bestiality, and idol-worship which is permitted by the media. That some things are still taboo is a miracle. But I don't believe in 'thought crimes' in the secular sense...
If this guy is guilty, so too are all the producers, writers, and actors who produce the smut which hollywood creates...