I think you're being too hard on him here. It looks to me like both sides fucked up in a number of ways.
Their gave their "friend", a completely inexperienced unknown writer, 20.000 for a poem. This "friend" took the money, spent it but refused to sign the contract on some bogus pseudo spiritual objection. Later he became more and more upset that notch and team made a ton of money.
To me this sounds like jealousy and greed.
They had a general agreement and by taking the money he basically agreed to the arrangement.
I think they could have easily taken this guy to court and won. Technically, Microsoft can sue the crap out of him for giving away something they have bought and paid for.