You get an exception, you get an exception, everyone gets an exception.
If he was a Legacy donor (not likely if he is in the endzone) then he agreed to make a donation in exhange for seats for the life of the donor, plus passed down the right for one generation. He knew the rules when he made the donation.
Good on BYU for following the rules. I am sure someone just as passionate and willing to donate will fill those seats.