By making a topic for this, it is the hope that we can just ignore him in the thread where he butts in, and take the quarrel here, and just link to here from the thread.
The reason this is useful is that if you answer him he will answer back over and over, and when he finds no real arguments he uses troll tactics, and this goes on "forever".
This ruins real conversation and the memo atmosphere by making everything into a mudfight, and wastes everyone's time. And fighting him only makes him a more invigorated/trained troll.