First, it is not related to United Nation or its affiliated organisation.
Second it is not a court of law, of course it has nothing to do with UNCLOS or know anything about how UNCLOS was set up 25 years ago by nations including China on what can be arbitrate and what cannot be arbitrate.
Third, the current arbitrators did not follow arbitration laws to employ impartial officials for this arbitration.
Lastly these arbitrators can be sued for corruption and other crilmes for misrepresenting UNCLOS law.