Ignorance and bigotry exist across all groups. Age, culture, religion, class, and education don't excuse it or make it acceptable - period. So, I think the question itself is irrelevant.
But I am also curious why you know the political views of your grocery bagger, unless you know them personally, of course.
"I couldn't help but notice that you've separately bagged the zucchini and the KY, what's that all about?"
"Don't talk to me! I don't want AIDS, sinner!"
"Whoa whoa, man, relax. I'm buying these for.. my sister. Uh.. hey, why do you hate gays?"
"Like all Oxford alumni I am a member of the Order of the Grocery Baggers. We have pledged to fight the deflowering of anuses."
"Oh, can I be right back? I forgot the whipped cream."
"Burn in hell!"