Couldn't agree more. The solution isn't to make this assistant apologize profusely. It's a reasonable mistake to make. Women of color are extraordinarily unusual in this position.

This isn't an instance of bias. It's a mistake based on simple base rate prevalence. No harm was done here and no harm was meant. Now, that doesn't mean that all forms of what people have taken to calling 'microaggressions' are harmless - some of them are harmful. This is just pretty clearly not one of them.