In his own mind B.O. had to articulate the abortion debate in his terms, thus framing the arguments to his satisfaction. The protests and the preliminaries were an affront to his ego. Had he given a traditional commencement speech, he would have lost the bully pulpit opportunity and possibly have been accused of avoiding the topic. So all those grads worried about losing their commencement to the controversy had to endure the O trying to out-debate the majority of Americans.
Your post is one illustration of how, through the sacrificial work of a small band of courageous activists, we now have the initiative.
Armies that have the initiative, and keep it, win battles. Every time.
Obama, conversely, lost the initiative today.
To reiterate: Our job now is to keep the initiative. If we do, we will win.