That's still no excuse. Look at it this way:
In Iowa, if Iowa and Iowa State both sell out home games on the same day (which frequently happens), 130,000 out of 3.2 million people have attended a football game on the same day.
In Minneapolis, if both the Gophers and Vikings were to sell out in the same weekend that would be 116,000 out of 3.6 million people have attended a football game over two days - which would make it logistically quite easy for the same person to attend both events - something which is impossible in the Iowa scenario.
That doesn't account for anyone in the rest of the state - just the metro area.
Your scenario is compelling but I think it just comes down to the Vikings killing Gopher football. They sucked all the football oxygen off campus.