Yes, the “slow mode” referenced is the right idea in these cases. Better to follow up there.
I do think @falco’s idea of how to automatically trigger this based on topic velocity is solid. The only thing I’d add is once velocity gets high enough, you probably need to temporarily prevent new users from posting as well – otherwise people could circumvent the speed posting checks by creating new burner accounts.
(I think a massive influx of new posters is also kind of a problem in those scenarios, even if those new posters are well-intentioned.)