I understand that you instacalled here. But you posted your question to this forum, which indicates you are thinking you might not have made the correct play in so doing. I'm just trying to encourage you not to rethink your play here for even one second. I know you think I'm weak-tight, so I figure my encouragement not to play weak-tight may be worth more than some people's.
His play is correct because his equity in the pot is greater than what he has to put in, in order to be all-in, and because he has folding equity. He gains more folding equity if you ask yourself questions like "why am I in this position against this guy" and think about folding.