Is it just me or can nobody comment on other topics? I've tried to comment on the forums and can't find a reply option on any of the topics, beside my own.
We've adopted the same forums implementation from PCPartPicker - there it retires topics after a certain period of inactivity. For PCPartPicker I believe that's two weeks, but there's a lot more discussion activity that takes place there. I'll look into making the lock period longer here. (We implemented the two week time period when people started bumping multiple-year-old topics repeatedly as a sort of spam/troll tactic.)