Actually, I’ve referred to a lot of adult males as boys, as in “He’s a big boy”, or, “That boy is going to be in a world of hurt!” - and those where whites, not blacks.
I’ll agree a lot of blacks will take offense, and I’ll agree it isn’t a smart remark to make - but it could reflect a total LACK of prejudice.
I don’t know enough about Rep Davis to know, but it could be either. There is no indication in context that he was saying something like, “Boy, bring me a mint!”