From a comment in a Facebook group:
1. The desire to fuck anything, legal or not, ethical or not, is given by nature, or the universe.
2. The social contract may or may not criminalise the thoughts and contemplations of 1.
3. Usually if 1. is followed by corporeal actions, it becomes of graver concern.
4. The social contract almost always criminalise a subset of 3.
In general, I think that treating people badly because they are weird at 1. is uncalled for. We should be policing 3. Meanwhile it is naive to assume that 1. will follow 3. It may or may not be cruel to entice our neighbours to commit crimes, when we know that as soon as they lose control of themselves, they are guilty of crimes. Whether this constitutes entrapment or not is a fun and dangerous discussion.