Due process isn’t lost. The VA is an administrative agency, meaning Congress has authorized them to do a variety of things, including make rules and hold hearings. The letter explains how to object. And if you still don’t like what the agency decides, you can go to court.
My guess is that the VA is acting legally under the laws Congress wrote.
So there would be nothing wrong with the VA issuing death penalties? The obvious question -who will enforce such verdicts?
Innocent until proven guilty is NOT guilty until proven innocent.