I always thought that in football when you had the ball the object was to score points. It didn’t matter what the time was left in the game, or how many points you or the other team had, your job was to score points. That’s not “running up the score”, it’s playing the game. My coach always told me you play the game for the whole game, you don’t quit, whether it’s the start or end of the game. Laying down for your opponent is a sign of disrespect, that you have pity for them. A good opponent doesn’t want pity, they want respect, and you give that by playing them with your best effort. You shouldn’t feel bad for the other team because it’s not what they want or should want. Neither should you feel bad for playing the game hard every play and every minute. Play tough but play fair. Respect your opponent. And be friends after the game.
I didn't watch the end of the game but generally in a blowout backup players come out at the end. They are playing in the National Championship game, so I would expect them to give their best effort because for a lot of them this game will be the pinnacle of their football career.