Welcome to the ride, friend.
There's a general dislike of kittypets due to the code, which is understandable, but what I was going for more specifically is the fact that Tigerclaw showed no ill will when he was told that Firepaw was a kittypet right when they first met, and then suddenly started insulting him and his ancestry the next day. That's inconsistency - if they wanted to portray him as a generally unpleasant cat, why make him be polite to Firepaw when they first meet?