The Secret Service says the agent opened fire at the suspect, who "did not fire or get off any shots at our agent," according to acting director Ronald Rowe.
I'm pretty sure it's been confirmed that he did not. He didn't even have a line of sight of Trump and was (apparently) still waiting for that opportunity.
Florida has a dumbass law where you can open carry while hunting and fishing. Dude could just say he was hunting anacondas or whatever they kill in Florida
Also, that's like the least insane thing about Florida. They banned open carry in public but allow permit-free(!) concealed carry. Most states allow open carry and require permits for concealed.