The longer you're in the pile, the greater a chance that the ball gets taken away. (But they want to prevent fights late in games, so that's probably why the rule's in place to prevent pulling players off the pile.)
I like how Temple - had they won - were going to bring out all the seniors, regardless of position, into the victory formation to take the knees to end the game; that's great "all one team/family" mentality and imagery...so of course they lost the game