From Twitch Emote Guidelines:

Prohibited: "Nudity, such as depictions and imitations of nude torsos, buttocks, genitals, and anuses."

This prohibition on emotes has been applied to emotes which are technically unclothed, but feature animals, which are not generally considered nude when unclothed.

In short, please unban cat butt. There is no reason to ban cat butt emotes.