He put his life on the line for Terry because he was Terry, and the DCAU guys love Terry. They always went out of their way to have Bruce be a dick to his sidekicks and make Terry Sue out to be the One True Batman.

Hell, he got shot up one time and then Bruce ignored him? That isn't even half the fucking-over Tim got in Return of the Joker. I mean hell, at least Grayson actually got invited back.