The best opposite to "pedantry" I can come up with is "pragmatic." Pragmatism is a relatively good value on Less Wrong, but I don't see a good application.

Yours seems good. It concedes the argument attempted to be raised, shutting off further discussion - a very desirable quality when dealing with somebody who is specifically looking for something to argue with - and rebuts the fundamental problem, redirecting future attention there. (Minor shift for reasons I have trouble explicating, but which seems a stronger, slightly harsher version of the sentiment - "Technically correct. Also irrelevant.") If it's used appropriately, and consistently, I think it could become an applause-light within the sub-culture here.