a) Did the author really expect that he would be getting royalties to all the Minecraft end text teatowels and fridge magnets as part of the deal? Clearly, the success of these products is largely correlated with the success of the game rather than the importance of what he wrote.
b) If I had wanted to make merch with this text on it last week but had been deterred by fear of M$ lawyers, I wouldn't really feel any different about it after the author 'releasing the poem under CC'. His claim to own the rights in the first place is totally dubious. He seems erratic and will probably go on to perform other stunts and legalistic trolling before he gets bored.
b) If I had wanted to make merch with this text on it last week but had been deterred by fear of M$ lawyers, I wouldn't really feel any different about it after the author 'releasing the poem under CC'. His claim to own the rights in the first place is totally dubious. He seems erratic and will probably go on to perform other stunts and legalistic trolling before he gets bored.