Not getting into the moral question on this one. I think their policy is pretty dodgy (especially since Starforce should prevent you copying the CD, which negates the only real justification for the policy) After all, there are plenty of things that could be wrong you couldn't find out without opening the wrapping (also skipping the whole "Is Starforce Wrong?" argument. I don't know enough and I generally only play old games so it doesn't affect me anyway)
Just thought I'd point out that technically what you did was fraud and you've just admitted it in a public forum. I haven't got a personal problem, especially since the game should be perfectly resellable but Amazon could try hunting you down through here if they felt vindictive (which big companies sometimes do.)
Don't worry, I'm sure we'll all come up with plenty of ingenious ways to break you out of prison. After all, we AGers have been practicing that sort of stuff for years.