The USCoC is not a court that hears controversies for takings. Any federal district court can hear cases and controversies regarding a takings. See Sisti. US CoC was created by Congress to only entertain monetary damage claims against the gov for more than $10,000 under the Tucker Act. It has no other purpose.
My main point here is that the USCFC has not been asked to rule whether or not a nationalization has occurred. They are just being asked to determine if the government has taken actions that require a payment to shareholders or the companies, and if so, in what amount.
I don't see why that matters. If this was a nationalization then the courts would have the authority to rule as such and provide the remedy. If there was no economic value due to the government takings and no compensation provided, isn't that a nationalization? Or are you saying there was a takings but there was still some economic value despite effectively taking 100% of the net worth of the companies.
The NWS was a taking (because it's legal, as the Supreme Court ruled) as far as the USCFC/appeals is concerned. It was a breach of the implied covenant of good faith and fair dealing as far as the DC District Court/appeals is concerned.
So which one wins? A constitutional violation or a contractual right?
If the CFC court wins I don't see why it is not possible for them to rule on nationalization pay the remedy and wipe out shareholders forever.