I had not heard about Hamilton. Hamilton was the guy taken out by the cut block-- I disagree with your coach as it was a good call and the play demonstrated the reason we have the rule -- he is our best defensive player and if he is out it will suck to lose our best defensive player and best offensive and special teams player in the same game, not to mention another defensive line starter, who happened to play the position that should have defended that last first down run.
Hamilton actually did try to play in the fourth quarter but was not himself obviously.
I really think that having Grant in the second half might have been the difference in this game.
Anyway, it can't be as bad as our basketball team last year, when we were down to seven scholarship players and a 6'2" guard had to play considerable minutes at power forward.