Comment on the behavior of a user in a thread and suggest ending the discussion with them.
I can't believe this thread is continuing! I must point out the obvious, old friend, you are dealing with yet another contrarian/troll who will never admit being wrong. All of us have caught him being incorrect multiple times. He'll just continue coming back for more because you are feeding him and he gets some perverse something from that. Your time is too valuable and he must have little else to occupy him. I'd suggest letting the thread wither on the vine, anyone who matters other than yourself has already left. I doubt I will be checking back anymore either.