25k can make a huge difference if it's around the bubble stages for cashing if he's short on chips. A 100k chip he would have to get much further on without busting to bring it into the game so the 25k might work better as he has a better chance to get to the point the 25k chips are brought in. If he doubles up off the 25k plus whatever else he has then the guy buys more time to get deeper in the tournament and potentilly deeper in the money if they are at that stage.
The other option is if he busts prior to this point of the tournament and knows a friend who is still left that don't mind cheating he could sell the chip to him for a percentage of his cash or whatever terms they come to.
I just have a hard time believing a guy with three circuit rings and tournament experience would do something so stupid for a souvenir. He never got caught taking a chip before for other wins whether he tried to or not but why take one now?