I support archiving topics that haven't had new posts in 3+ months.

Unfortunately, the fact the troll in question hasn't been dealt with by moderators means they're either asleep at the wheel due to COVID or what he's doing isn't technically against the ToS. I find the latter more likely, though the former is a possibility I can't entirely discount. Either way, archiving old threads would deal with the issue and prevent other trolls from exploiting the same loophole, so I feel it's a more viable course of action moving forward.