The company is registered in the US. US law can therefore apply. In fact USA claims jurisdiction where it's very shady to do so (for example just for payments made in USD)

That's the idea, I think. Of all the submarines that could reach that depth it was the only one with no certification.

That's what needs to change. If there was enough support internationally, the UN could facilitate a treaty being signed between nations with uniform regulations on submersibles. Then it wouldn't matter if it was international waters.