chicken and fish = needed protein. He was never a big eater even as a veggie (therefore hard to get needed protein from things like soy and nuts). Since he's such a serious dancer he needs a lot more protein in his body than a reg. veg diet can give, to repair damage to the muscles.
My daughters are all competitive gymnasts and after every workout they have to mend their bodies within an hour with high-protein foods. Carbs before and during workout, protein after. otherwise it can slow you down and give you stomachaches. But the protein from some kind of meat (usually pref. chicken or fish because of low fat content) is preferred. Otherwise they'd have to eat LOADS of nuts to repair the little rips and tears their muscles endure. Same thing would have to go for Michael. I'd say for the MOST part he prefers veggie lifestyle, but that protein boost from chicken and fish is necessary for his continued health as a serious dancer and high metabolism.
Haven't heard of him eating RED meat though. i.e. beef and pork. So if he's gonna eat chicken, might as well be some GOOD chicken!!