Yes it is allowed. There are no restriction on the use of galvanized pipe for natural gas piping systems in the Florida Fuel Gas Code or the Florida Residential Code.
404.11.1 galvanizing does not deem zinc coating as adequate protection for underground gas piping. Although I also could not find language for galvanized piping above ground, I would question 403.3 other materials as to whether it needs to be investigated and tested that it is safe and suitable for the proposed use and that it is recommended by the manufacturer for that service and approved by the code official.
I agree that galvanized piping can be used above ground for a gas piping.