This seems like a pretty neat idea! I like the governance model too. Only issue I see here is the initial cost factor is quite high. I am curious what would happen with a collection of less expensive, floating shipping container type homes are introduced... Providing a network of floating utilities actually makes a floating city quite doable. The white papers on the primary site [3] are quite interesting reading.
[1] https://futurism.com/floating-island-project-high-seas/
[2] https://www.cnbc.com/2018/05/18/floating-island-is-planned-with-government-cryptocurrency-and-houses.html
[3] https://www.seasteading.org/floating-city-project/