That's not how it came across to me at least. His reply came across as a reasonable part of a discussion, and you came across as being a total asshole. Your assertion it was a "blatant replication of his smugness" just reinforces that impression to me.

If that's not the impression you want to give, you might want to reconsider your approach.

I'm not interested in people's impressions of me (and it doesn't bother me a bit if they think I'm an asshole -- I guess I'm just selfless that way).

That doesn't make you selfless, that makes you selfish, because you only care about what you think of your self and ignore what others think of you.

Enjoy it while the delusion of being right lasts!