Actually, he was right, and you are mistaken.
He knows full well that he's mistaken, and is just enjoying how much
valuable time he can get others to waste trying to show him the light.
For those joining in late, here's a summary of the discussion so far:
Sage: The main function can return anything it wants to.
Everyone: No it can't, and here's the proof from the standard.
Sage: You're wrong.
Everyone: No, see it says quite clearly that it must return an int.
Sage: You're wrong. You're an idiot.
Everyone: No, really, the standard is explicit on this point.
Sage: You're wrong. You can't even understand simple English.
Everyone: Look, the people who wrote the standard are agreeing with us.
Sage: You're all wrong.
and so on ad infinitum. There is no point at all in continuing, and
hasn't been for a couple of weeks now. Nobody could possibly be as
dense as he is pretending to be. It's been a masterful job of trolling,
but please can't we all LET IT GO! He will never admit we're right,
even if the entire ANSI standards group, the signers of the US
Constitution, Jesus, Buddha, Gandhi, and all five members of the Beatles
showed up at his door and told him he was wrong.
There should be no more proof required than the quote he proudly
displays in his signature, and presumably lives his life by: