If the discussions have been originated by him or otherwise are oriented towards discussing things that he's brought up, then yes, it's perfectly reasonable that you should either 1. abstain from the discussion or else 2. respond to the points which are actually at issue.
Your opinion has been duly noted and dismissed. It is a DISCUSSION. I address comments by posters in the same way I do on discussion on other topics.
There's a good reason I don't take part in discussion threads by certain people on this forum. I don't care what the topic is about. I'm not touching discussions with certain posters with a 10 foot pole.
So you aren't interested in topics but rather the people discussing them? Got it.
There is a good reason I don't get involved with discussions about Catholicism. It doesn't interest me ... where as discussions regarding the death penalty, child abuse, domestic sexual and physical abuse (including rape), abortion, divorce, hate crime laws, gay marriage, etc. DO interest me.
Here's an idea: quit playing thread monitor. It isn't your job. A good portion of the time I ignore your responses as well ... for good reason.