Is racist quite the right word here? I'm Welsh, but have only a very slight Welsh accent and may sound to some like a southern Englishman. Years ago, I was in Hull visiting a mate there, and as we were walking down a particular street, my mate told me to keep my gob shut for a bit as a southerner was liable to be punched. Was this anti-southerner racism?
I don't think so. I think the two situations are similar and that it is nasty, narrow-minded bigotry. But I don't think it is helpful to call it racist.