Without information about the external constraints on your hiring, I'm not sure it would really constitute meaningful evidence (e.g., if the entire available employment pool was black, hiring only blacks wouldn't be evidence that the process you had implemented wasn't biased, just that the bias has no opportunity to manifest.)

(This is the kind of thing that would work mostly to burden shift, but then the burden would already, IMO, be on the person making the accusation from the start.)

OTOH, it would be very challenging (though not impossible) for anyone to have evidence that your system was biased against blacks with a hired-all-blacks outcome.

It is entirely possible to find evidence of things that turn out to be false. For example, you could take the seemingly chaotic retrograde motion of the planets in the night sky as evidence of the existence of gods with self-determination. We know know that isn't true, we have better explanations for that phenomenon (notably the notion of heliocentricity).

The planets moving differently from the stars was never proof that there were gods up there, but evidence? Sure, it was evidence. Evidence can be of various qualities, evidence of thins has to be judged critically, and weighed against the alternatives.

Facts which do not provide a basis for comparisons of how different values on that axis are treated are not much evidence for or against bias, this include facts about outcome (e.g., all the people I hired are black, etc.) without additional information from which the expected outcome in the absence of bias can be inferred.