muting can take the aggravation out of arguing with the wall; if you tell someone that you simply arent going to argue a subject past a specified point, and they dont bother listening to you, then mute may be the best option
there are some subjects that some people are unreasonable about, and they are usually the ones that the people identify themselves with, or are central to their worldview
[edit - and thanks for the reSteem! I was wondering where all those comments came from!
I do see your point about engagement with that person in the future; I'll have to think about that]