I'm not a Meta fan or anything, but this does seem kind of tricky to deal with. Specifically that pages/topics which get sudden influx of activity at once can look similar to a coordinated spam campaign. Especially if combined with being flagged opponents who don't want to see that content. It seems like it could be hard to tell the two apart, or at least the false positives seem hard to control.

Can anyone with more experience on these kinds of spam/fraud detection systems could chime in?