The Strata is kinda locked into what it can do to keep Jonny out thanks to many home owner protections.
Miriam owns that condo, so it will be super hard to get a court to agree to force her to sell it. They might banned Jonny but again, very hard to get a court to agree to that once he inherits it.
All in all I don't think there is much the strata can really do aside from start a long process of documenting and fining Jonny for all his infractions of the strata rules and after years maybe decades they can go to a judge with all that proof and even then they don't stand a good chance of winning.
I mean it's a good thing that a condo board can't really force an owner to sell just because they're assholes who everyone detests, even if that asshole tanks the property values for everyone else. As long as Jonny doesn't break any laws he can probably snuggle up in that condo until the day his bloated, decayed corpse is extracted weeks after his death.