Yes, generally speaking legal threats which are not made in good faith can cross the line into being illegal, e.g. extortion. But that isn’t because they violate DMCA 512(f). And I think it a a bit of a stretch to say that abusing ContentID is a legal threat. The number of ContentID claims that result in legal action rounds to zero.

Had anyone ever successfully sued in response to a false non-DMCA copyright claim?