"I have a respiratory illness that makes it impossible for me to wear a mask."
"Under HIPPA laws, my personal medical history is confidential, and you cannot question me on my medical condition."
"Still won't let me in? So it's the policy of your company to discriminate against people with disabilities?" (make sure you're recording with your phone)
Totally debunked B.S.
You’d be laughed at as you were thrown out; and good luck suing.