That's an issue.
I can think of 3 reasons you're less likely to see deaths from out of state residents
1) The biggest source of deaths in most states (I'd assume the same for FL) is LTC facilities, their residents are all FL residents. People who live in their own homes are able to protect themselves better.
Total FL deaths reported by DOH: 3327
From LTCF: 1625
Regarding which people would be better protected, I'd argue a facility is easier to isolate. Many, many condos and developments here are restricted to people 55+. They still have to source their supplies from the same places as the rest of us, but then bring those germs back with them into their high-risk communities. Elevators, handrails, mail distribution, and other common areas are all ripe for spreading.
2) Anyone who can make FL their primary residence will, so presumably most snowbirds are FL residents.
This isn't true. Most of them keep their primary residences elsewhere for many reasons, including medical, legal, and financial. The average snowbird lives in FL for approximately 4-5 months, so technically they shouldn't be claiming FL residence, either.
3) Snowbirds (especially those who aren't FL residents) are generally people who are (relatively) younger / semi-retired.
This just isn't the reality. IME, the average snowbird is fully retired, and is between 50 and 80 years old.