Thank you @Alexandre @espenser @blue85 and others who have contributed to the discussion.
Our son talked to many people in his school and surrounding community and made his decision. He picked Michigan!
Here is his reasoning:
While GT was his top choice for better part of the pre-notification period, he now thinks it was mostly superficial. With UM (and a few other very good) admissions in hand, he thought more about what he wants to do in the context of the colleges that offered him a spot. He argues that this is where he started leaning towards UM (do we have a lawyer in the making or what? 
He says that the notification timing did hurt his ego and made him react and he gave reasons that were not rational…but really, he says he will have fun be happy at Michigan.
He applied to Michigan partly because he had looked at PPE program (Thanks for bringing it up again, Alexandre - it does sound like a good program, please let me know if you have any more information about the outcome of students who went through PPE) and how it tied to his interests (academic and extracurricular - he was a MUN, JSA & Debate kid who took Philosophy classes in HS). He even wrote about this program in his essay.
He thinks he needs a broad based major like Econ and add a minor (or courses) in IR/public policy areas. He will discuss this more when he meets his adviser. There are some others who are advising him to go into business school, but he is still undecided about that path. If he was 100% certain that IR is the way to go he would have applied to SFS @ GT (he applied and got into College). Class sizes, Jesuit values & mission, Washington DC and many other intangibles do set GT apart in a class of its own and it would have been a fine choice.
Being a 49er fan, he said if it is good enough for Harbaugh, it is good enough for me
Many thanks to all who responded, looking forward to the next four years!
Go Blue!