For your SIL, I could say more, but probably on this site I don't need to.

Sometimes when I meet potential adopters at the shelter, they ask me "What's wrong with these cats that they are here?"

"Nothing," I say. Someone decided they didn't like the cat and dumped it. Often, these people are incredulous. BUT IT HAPPENS ALL THE TIME

May the kitty be picked up and find a loving, permanent home. That is, before something terrible happens to him.