I think what LW is really asking - the reason they wrote to an advice columnist about a brief encounter with someone they only see every 6 months and have no personal relationship with - is this:

"I wanted to be mean to this guy I saw doing his job and not harming me in any way, but I thought any words I said might incriminate me. Can you give me a script that expresses my disapproving sneer verbally, but still gives me plausible deniability about being a bigot? So that I can be mean to people but if anyone complains, I can pretend that they're oversensitive and crazy and reading things into what I said."

Which Carolyn appropriately shut down hard.