China ignores the Law of the Sea Treaty right now:
China on Wednesday rejected an arbitration tribunal's ruling giving it six months to respond to a case filed by the Philippines over disputed waters, saying it has no plans to take part.
China signed the treaty yet doesn't think it is important to obey.
In what world do you have to live in to think our joining the Law of the Sea Treaty (LOST) would have any positive effect on Chinese thinking?
Given Chinese thinking, if we join they'll conclude that we must go along with China's interpretation of the treaty. Otherwise, why would we join? Clearly it would be ratification of Chinese views.
A strong United States Navy is the best defense against China ignoring international law--not some farcical aquatic ceremony.