Glad to see the OP is from Florida. Most state park sites are generally unavailable to us during the snowbird season.
The snowbirds have to expend a considerable amount of time and effort in order to book their sites < 365 days in advance and have to do quite a bit of moving from site to site and park to park in order to spend the season down here.
The rude dude certainly is part of this dance and should know better than to bother anyone with Florida tags in a state park during the season.
Hats off to the OP for:
-getting a site this time of year
-staying until check-out time and enjoying the park until it was time to check-out
FWIW Florida welcomes the non-residents with no difference in prices vs. Florida residents. Most are fine with this, just don't expedite our departure when we are fortunate enough to get a site.