I read through that and did so again now. What I get from the section is, if an account is forked out, they can go ahead and try to run a version of the blockchain where they're not.

re: HF9

I hadn't heard about that. There seemed to be a reluctance to do anything like that, even to obviously bad actors, in the time I've been here, other than starting to pull whatever initial delegation from the Steem account.