You can't try a Florida case using California regs.
When reading this I just keep coming back to the California prop 65 warnings that have become so common place on so many consumer products today.
If all this stuff is known by the state of California to cause cancer, how can a corporation sell them and not be at all negligent or liable for doing so, even though California has told us that it is dangerous. Except that's what the warning label is for. It's the same reason why Disney warns people with medical conditions not to ride certain attractions.
If Disney provides adequate and reasonable warning about potential health dangers to all guests and have operations that comply with best practices and local regulation, it becomes extremely difficult to prevail in a suit. That being said, it's very easy for anyone to file a lawsuit, which probably is the most problematic part (PR wise anyway).
You're not trying it based on regulations. Negligence is a common law definition.
So the standard a jury would be asked if, "what would a reasonable theme park operator do"
State regulations would be irrelevant.
You can be fully compliant with regulations, and still held liable for negligence. (though violation of a regulation becomes per se negligence).
Warnings and waivers are not typically enough to waive liability. I can't open a burger stand and decide to sell spoiled meat and simply have a little sign that says, "You accept the risk that your burger may have E.Coli" (Even apart from regulations, that would be obvious negligence).
Every business operator has an inherent unwaivable duty to provide for the public safety.
Of course, there are things that are inherently dangerous, even after all precautions are taken. And that's where you get into the "duty to warn." That's where we get the ride warnings that the blinking lights can cause seizures, etc.
For something like Coronavirus, if you really wanted to rely upon "assumption of risk," you'd need far more than a sign. Probably loud announcements as you enter the park, "We are unable to control the spread of Coronavirus. By entering the park, you accept that there is a high likelihood that you may become infected with Coronavirus, with a 0.5-2% risk of death." Have that playing over and over on the loud speakers. Then have them sign and notarize a statement that they appreciate the risk of Covid-19 and accept that they risk hospitalization, respiratory failure and death.
Not a great way to enter the happiest place on earth.
Now, maybe you don't like that the law operates that way -- But it simply is how the law operates.