The fact that the author has to 'assume' would concede the fact that he is only guessing based on the data that he finds convient.
Florida's population is 15 million right now. Who in their right mind wants to add another 10 million to that total?
The use of 'assume' seems like a way to make clear the premise for the argument. It also appears to be a literary mechanism designed to soften some of the impact to long held (but faulty) premises held by all too many.
As for the accuracy, drive around and look. Better yet, check with the Property Appraiser's office in your town.
All of the above is separate from the unavoidable fact those the author called "Communism Lite" did work diligently for, and succeeded in passing, the laws and regs that resulted in the takings of all that land.
And that land can't now be used for homes, so the increasing population of Florida MUST be crowded into those urban enclaves described by the author.
I don't understand your seeming unhappiness with the article as it seems to pose an interesting premise and is difficult to refute on either its premise or the basic facts.
Whether you or I want more people in Florida is hardly the issue. Want 'em or not, they are coming.
The author seems to be discussing the wisdom of departing from the historically proven American private home on private land in favor of the "urban enclaves" so beloved by Communism Lite advocates