Rita would probably say you were having "a blonde moment", Jayne.
The speaker of the poem is Dove herself, we assume, an older black woman in traffic, irritated by lots of giggling blonde girls taking too long to cross the road. Somewhere behind her is a statue of the Confederate general Stonewall Jackson, so the link is made between the girls' whiteness and historical, institutional racism, the suggestion being that the girls are, or will become, part of that problem. Bill is saying that if you accept that institutional racism is still a problem then the speaker is justified, or at least her anger is, and if you don't then her anger isn't justified and the poem is racist against the girls. Others might say that even if you accept the existence of institutional racism her anger at these girls, or at least the focus on their blondeness/whiteness, is still unjustified.
I suppose one
could argue (if one wanted to) that the speaker is sexist and ageist as well. I think, as John says, that the poem is a depiction of the speaker's heightened emotional state. It's a portrait of anger, which doesn't always follow logic, and doesn't necessarily have to in order to be justified.
Of course there's a third option, that whether the poem is racist or not is less interesting than the fact that the discussion it has provoked demonstrates how hard it is to write about this stuff.
I Iove Dove's poem "Hades Pitch".
Cross posted with Bill (oh, and Aaron and Andrew).