I don't know why it should be illegal to call someone a racist. Being a racist and talking about it should be protected free speech, so calling someone a racist isn't the same as accusing them of a crime.
When the woman said the man should be sent to prison, they should have reminded her that being prejudice against obese, loud mouthed rude people isn't a crime, but she could be banned from the store for abusing their checkout system and for disrupting regular commerce.
When the woman said the man should be sent to prison, they should have reminded her that being prejudice against obese, loud mouthed rude people isn't a crime, but she could be banned from the store for abusing their checkout system and for disrupting regular commerce.