In this context, it seems like "self-serving" is the same as "team/program-serving."
Yeah, if you're predisposed to 'hating' a coach, this just fuels you. If you're objective, it's a coach/mentor/caretaker of a young man, seeing him into the next stage of his life. And it doesn't hurt to show the next set of recruits that you 'care' for a player even when he's no longer in a position to win games for you.
That all said, in Mal's position, it might have been a long, humiliating night, compounded by a JB presence, if he hadn't been selected 'early enough.' Mal already looked far more despondent than grateful for being selected — as if some 'draft promise' went unfulfilled.
And, who knows — don't the player and family (and agent) have a say re: who's at the table? Mal's folks might not have been thrilled at JB's comments, and would have rejected the idea even if JB had wanted to show support.