We just had a thread revived after 2 years and some of the comments are perhaps not so desirable -- who wants to be reminded about a personal tragedy. But even at a mundane level after about 3 months additional comments are not adding any value. If so, a new thread is probably a better way to bring the old topic up (a link for reference is always possible).
Would not think locking threads to block additional comments is all the difficult programmatically and we've certainly seen the due to administrative intervention.Yes, there are those here who squirrel away old posts in order to use them against someone. In the case you cite, it was despicable. But it also had the unintended consequence of reminding everyone what.a total dirtbag the poster is. So it was actually good in the end. I'm sure the same dirtbag has stuff on me and don't care if he uses it. The last time he did this it was actually info from an old PM. And it backfired on him. He'll never learn, I guess.
Anyway, I'd leave well enough alone.
Sometimes the topic is still relevant today and merits further discussion. The problem with the retreads is that sometimes the thread is already too long and bulky and adding one more post on a thread that already has a hundred replies seems pointless, whereas if someone had simply started a new thread on the same subject and linked the old thread the conversation would flow more freely.