I don't care what anybody else says about you Keyser, you're an OK guy.
Doing what you did just made you look better and him worse in the manager's eyes. You didn't pre-judge a customer and got rewarded for it and you gave a sale to a stuggling salesman, even though he didn't deserve it.
I give the whole "donate to a charity in his name" thing some more thought. It worked in my uncle's case because he had died and therefore couldn't do anything about it. In this case, though, it could back-fire. He can claim he did donate the money and make himself look better for something he didn't do.
Donate it in your name and put up the plaque in your office, just to piss him off. (Look, I made so much money on the deal your turned down, I have enough to donate to charity.)
Just an additional thought.
To say it again, "You da man!!"