Your argument seems to focus on the "best site for a stadium" while others (including me) are focusing on what will actually happen given all the circumstances surrounding the decision.In reality students aren't coming out for football games as it is and all many of them have to do is walk a couple of hundred yards. In the mean time you have many multiples of long time residents of this region, not transients, who form your long term ticket base, not wanting to deal with the PITA location and instead watch it on TV.
The inner harbor location is the same distance to the Dome by car as the back end of Skytop and almost a mile closer than Drumlins.
Heintz Field is around 4.5 miles from Pitt through a much denser city and across a major river.
Miami and SFla play 20 miles away from campus. UCLA is over 20 miles from the Rose Bowl.
The inner harbor location is about 3 miles by car from the middle of campus.
And yes SU would be out of the stadium business, but they would be the anchor tenant as opposed to other schools that use pro stadiums.