Yeah, in normal operation there's nothing wrong with letting people revive threads - it could do with some kind of warning/confirmation prompt, maybe, because you do get people who must have found threads in a search somewhere and didn't check the dates. If a thread is still relevant and the person wants to discuss it further, there's value in reviving that past discussion instead of starting from scratch.

Obviously that's not the intent when someone is maliciously bumping threads to disrupt the forum, but stopping that should be about the mods doing their theoretical job and stopping the one person, not taking away the ability from the rest of us.