I think the only time I would consider moderating an old question, other than spam, would be if a response contained a really bad personal attack that went undetected.
We don’t moderate old questions for being off-topic or unhelpful. Moderating for flame-baiting also wouldn’t be very lucrative retroactively because the bait either worked or it didn’t—the conversation is done now so that doesn’t matter as much.
Moderators don’t actively comb through old questions without a spam alert, though. So it’s unlikely that any moderation decisions would need to be made in the first place.