Unfortunately, it's not that easy. Bitchat is permissionless, so there is not banning or kicking users. On top of that, the bot generates new nPubs constantly to circumvent users muting it. It even does PoW to avoid being filtered that way, and the content is clearly AI generated, so there is no distinct word pattern that could be used to detect it. And since the messages travel via relays, you can't block its IP address either (which would be trivial to circumvent using VPNs anyways).

Someone is spending quite a bit of effort and compute time to make using Bitchat as annoying as possible.