There are currently 3 Rust communities across 3 instances: programming.dev, lemmyrs.org and this one (lemmy.ml). I know it's still very early for the migration from /r/rust, but it would split the community if there are so many options and nobody knows which is the "right" one. Currently this community has the most subscribers, but it would make sense if the Rust community finds its new home in one of the other instances.
lemmyrs.org seems like the logical solution if instance-wide rules are paramount and "non-negotiable"
personally I would love a programming-centric instance and programming.dev seems like a good way. Rust is not the only language I'm actively using (unfortunately :)). Maybe there can be community-specific rules that "enforce" the Rust CoC and the Rust community can find a home there?
Either way, the current situation has the most negative impact.