What gets me about this angle is why he didn't just submit his audition as a group act (something that's already allowed anyways).
And I understand that 'talent' is a broad spectrum, but AGT is a performative talent show. Being able to write good (in Russell's mind) music isn't something people would pay/tune-in to watch. So once again, why not do a group act? You can be the composer/keyboardist and let your band mates do the rest. Now you can use your talents in a way that actually fits the format!
Of course, I know the answer: Russ's ego won't let him share the spotlight.