I honestly wouldn't care. I might even laugh. People can say whatever they want, meanwhile, I can choose to listen or not or even discount what they say. Maybe I'm just not offended that easily.
Being a minority in America and growing up hearing sly and racist comments from both white and black people may have something to do with my being inured to this, however. The Gospel is just not offensive to me no matter where or how it is presented. It wasn't offensive to me back in the days when I was not a believer, either--I just ignored it, and quite a few people still do.
Maybe you wouldn’t, but I think it is entirely inappropriate for a graduation ceremony. Church, absolutely. She would have been entirely appropriate to thank God, and to attribute her success to him. Condeming non-believers or those of other religions to hell goes way too far.