Maybe he wasn't told he couldn't do engineering but he felt that he would not have as much support. Over a 10 year period Michigan awarded 1,284 degrees and 46 of those were to African American students. The percentage of African Americans at Michigan as a whole has been decreasing but I do not know what the last couple of years specifically for engineering is like.
I may have just felt that he would have been out of place. I know I would have been which is why I went to the military.
Of course he could have chosen Ga Tech if it was just academics and wanting more faces like his in the classroom.