I'm gonna go ahead and say that both participants in this argument are equally handicapped.
Yeah, he was acting like an immature little child dishing out empty threats, but if you really are old enough to have served through two tours then one would assume that you are mature enough to just ignore him.
Instead, you continued to argue with him to prove yourself and looked no more mature than him. Just disconnect from IRC next time and the problem will solve itself with him yelling in the dark.