I voted that it is normal. What isn't normal is that Bilbo would say it out loud. LOL

People are hardwired to get aroused by certain things. Every person has some sort of fetish, even if they don't want to talk about it or even admit it to themselves.

The folks that are into child porn are mentally flickted. The animal sex is sick as well.

Still, at the end of the day it's not thinking about such things that is criminal. Fantasy is just dandy. The acting out of such thoughts is sick.