It always happens when the teams are full and only one coach can turn, that someone appears singing well, and the other coaches wants to turn but can't. I don't believe what happend with Guy wasn't planned to be like that.
And I think maybe they will alllow the other coaches to turn for a 13th singer as well, that would explain why they are showing this controversy on Sunday. If not, there wouldnt be enough spots left for another episode on Monday.