The fix at the moment is a bit slapdash, essentially saying ‘skip over resetting user counts when you delete chats’, which should be analogous to the ‘skip over resetting user counts when they make topics or posts in chat’.
Discourse is complicated software though, so I’m not 100% certain at the moment that the counts / triggers modified on creation are 100% parallel to those modified on deletion. However, if you’re happy, I’m happy, and will merge this after a little bit more smoke testing on my end.
Re: normal topic rendering, I’d rather get to a point where you can’t render chats as normal topics at all, rather than making them work as both. There’s too much that can go wrong if we allow people to respond to chat topics with the normal Discourse flow, and vice versa.