i didnt say emotionless, but what kind of "master" would he be if he went against EVERYTHING he preaches, just because his "colleage" dies, something he knows is alays a possability? im sure he has feelings about it, but if its wrong for Anakin to get mad about his MOM dying, then yoda whose 800 years older, shouldnt get mad about Mace, or at least not fight with anger.
Look everyone feels anger, just like everyone feels fear. The problem is when someone gives in to anger fear etc and lets it dictate their actions. Anakin's problem was that he gave in to rage and massacred an entire tribe, including women and children.
Of course Yoda is going to be angry about someone killing his friend. Just so long as he doesn't let anger get the better of him.