Lawyer up and sue. This is coercion and that employee and business should be protected!
https://criminal.findlaw.com/criminal-charges/what-is-coercion-law.html
I got heckled tonight by some beta male who was 5'6" and 300+ lbs as I left the grocery store.
"Excuse me sir, can you not read?"
"Yes, I can read just fine."
"Did you not read the sign on the door"
"I did, must be you didn't, did you read the part in white at the bottom?"
(It states you're exempt if you have medical reasons prohibiting the use of a mask - my reason is I'm not medically dependant on the state making my healthcare choices)
"Reeeeeeeee, people like you ... Reeeee... My wife is in there shopping..."
"You have a nice day sir"
And even that was largely just taken straight from the pulpits/sermons of based preachers of the time.