I didn't think you were trolling.Edited to add: Not trolling, genuinely curious. I noticed some of the open for sale threads are over 2-3 years old, and the WTB threads go *many* back years.
Classifieds are different and mods certainly don't have time to monitor each one. It's the OPs responsibilty (and respectful duty to other members IMO) to lock a thread once the deal is complete. I hear TaT doesn't show the lock/close option, no idea if it shows the Report button either. Regardless, OP can get a message to site staff asking that it be closed.