The issue is that he walked out half way through training.
I don't mind him fighting with teammates in training, you see players leather each other behind the scenes and the managers don't give a f**k. They love it. Walking out half way through training is unbelievably childish. He's a great footballer but I'd say he's as dumb as they come.
I don't like the fighting at half time in a game. If a player is playing shit they know it and if some crap manager or team mate roasts them they just erode any confidence the player has left and they're even worse in the second half.
A bit of fire in training is good. But you can't be shouting at people to give more and then sulk of the rest of training yourself. Thick as a scaffold plank.