African American

You must be rightly proud

But ... what Mitch said is definitely offensive ... if you choose to view it that way. If you are inclined, so to speak.

However that's not the only interpretation, and the idea that by 'Americans' he meant 'Americans as a whole', i.e. including the subset of AA's ... is at least plausible.

If called upon to explain, that's what he'll say, and it'd be difficult to rhetorically prove he meant it ... the way we believe he meant it.

As such, I'd say his quip qualifies quite perfectly as dog-whistling, myself, because that's really the definition of the term ... as in 'we know how he really meant it, but a non-racist interpretation is still possible'.