One thing you can do (and I’ve done multiple times here on meta in the past) is lock certain users to trust level 0, which has fairly strict rate limits on how often people can post. That puts them in the “I want minimum levels of participation from this person” box.
Putting a specific topic in lockdown mode is something that has been discussed before and I tend to agree is correct, because some topics are farrrrr more controversial than others by their nature. See
I would like to see this happen automatically though (kind of the way we execute a timed close on topics with too many live unhandled flags) because otherwise we’re heaping a bunch more emotional labor on staff to somehow know when topics are heating up and take manual action.