It's not that cut and dried. Intent matters. And the courts have ruled as such before. There is clear precedent.
Florida is totally within its rights to decide that special districts such as RCID are no longer beneficial and should be eliminated. However, even though that is a legitimate action to take, they can't take that action for a prohibited reason. If they are taking the action specifically as a way of stifling political speech, it is prohibited. Think of it this way: In an "at-will employment" state, an employer can fire someone for any reason or no reason at all. But even in those states, if you can prove that you were fired because you were black, it is illegal. An action that is normally perfectly permissible becomes illegal because of the intent.
The question, of course, always comes down to whether or not you can prove the intent. Normally that is difficult. However, in this case, since DeSantis and the legislators have publicly and plainly said exactly why they are doing it, I don't think it would be a high bar to clear. You can never be sure what a court will do, of course, but I have a feeling that Disney could prevail on this if they choose to fight it in court.