The Cayman Islands are a British Overseas Territory. A seastead isn't going to be an overseas territory of a significant power in its own right that is also a NATO member and permanent UNSC seat holder.
True, but there are other offshore financial centers doing the same thing, which are not under the British umbrella, including several small European nations, several in the U.S. sphere of influence, Asian centers such as Singapore, and independent oddballs like Uruguay and Somalia. None of them have faced serious consequences of any sort.
The Cayman Islands are a British Overseas Territory. A seastead isn't going to be an overseas territory of a significant power in its own right that is also a NATO member and permanent UNSC seat holder.