Inviting obama to speak at Commencement is not the issue. One can object to that as being offensive due to his stance on abortion or think it's a great idea to have the first mixed race President speak to the graduating class. His speaking there doesn't violate flagrantly violate Catholic teachings and by itself wouldn't cause such an outcry.
The issue is giving obama an honorary degree, with a side issue of making the ceremony more about him than about celebrating the students' accomplishments. The honorary degree is the violation. Either Church doctrine means something or it doesn't. Clearly, ND, thanks to Fr. Jenkins, has said it doesn't.
A lot of folks have been saying that, and if it were just a speaking engagement I might (emphasis on might) agree. But for commencement speakers should challenge the students to higher ideals. There is no way this turd of a president could fill that function. I say the jerk should not be there in any capacity...dripping his sleaze on that stage.