It would be illegal because the Knicks were not compensated or gave permission. Sports teams make a great deal of money on licensing a are very protective of their trademarks because of it. They generally do not like others making money off of their trademarks without them getting something in return. It would be like some guy making his own Oakley fruit of the loom tshirts and selling them. You can pretty much bet the farm Oakley would have an issue with that.