University enrollment is a zero sum game, but not everything is. Positive discrimination in a zero sum game will indeed result in negative discrimination, but not by virtue of discrimination being subject to Newton's Third Law.
There is a school of philosophy that newton's laws of motion apply to the political realm - "any action taken to benefit a minority group will result in an equal and opposite counter-reaction".
I wouldn't be terribly far off if I described Sun Zu's "The Art of War" as Newton's laws of motion applied to game theory.