Going around topless and carrying are different from drawing out the gun in a public place.
To the tactical issue - the best bet is to flee or talk calmly to the individual.
Florida is a fun old person place. I've seen an old guy totally flip out in the Walgreens because he had to stand in line to get a birthday card. Threw it on the ground and stomped on it. Glad he wasn't carrying.
I also saw a gentleman drop stone cold dead at the ATM. Stream of urine crossed the parking lot. Freaked me out, went inside to tell them to call 91. Happens all the time, they said.
On the other hand, two old men - one with a NAA 22 mag and the other with a 22 mag derringer - shot a crook holding up a restaurant with a shotgun,once.