The op did not mention only companies that would be publicly sold. It said ALL OWNERSHIP of companies would be banned. So yeah, people can currently register their companies in whatever way they wish, but the op removes all the options that make the most sense for small companies. And I bet your example was just a partnership, and they wanted to feel fancy by calling it a board.
Poorly timed as the sub finally set on the British empire for the first time in over a century just a few months ago