A man also can get angry if he looks like Mike Tyson. As for a US presidential candidate, he is not allowed to get angry, till after he loses the election.
No one could have imagined, during the hundreds of years in which Americans profited by snatching Africans from their forests and mothers arms, that one day one of these Africans or their descendents would become president of this empire called America. But, as Captain Mimi al-Sherbini put it in his comedy: this is America, folks!