kelly, I think that the objection was that she identified HIM as "a rude boy" (as in, that this is a perennial character trait), which sounds as though it really isn't ordinarily the case.
That would bother my ordinarily rule-following, adult-pleasing DD, too.
On the other hand, "That is SOOOOO RUDE!!" or even "you are being very rude, {name}" is a very very different (and much more accurate, as it happens) statement. Because it isn't about the child as a person, but about a behavioral choice which was transient.
It's like the difference between:
You're a very selfish person,
versus
you are being selfish.
The one thing (rightly) refers to a behavioral choice and the other to a personal attribute. Now, I have known people who ARE just plain rude. Not situational, it's kinda who they are.
But they tend to be pretty callous and indifferent to the opinion of others, too.