Ugh, this makes me so sad. I'm sorry. I get cringy gaslighting vibes from the owner's response.
I feel like the response I expect would be more like, "Dang, I know who you're talking about. We'll talk to that person and assess their continued employment. We really want you here, so here's some free stuff for your trouble."

Not "Actually, no, uh, we're super not racist, but also, that couldn't have been us! That lady, who, again, was not an owner but who is definitely employed by us, was just trying to be nice! But I guess you wouldn't know about that. Look who's the racist now!"