An ATP is only required in the US to be a commander in a scheduled airline operation. In the operation you are requiring, only a commercial certificate is required. Common carriage does not really have anything to do with it.
There is no such thing as a frozen ATP in the US. They exist mostly in Europe where the holder has a commercial certificate and has completed all of the ATPL theory exams, but does not yet meet the flight time requirements to be granted an ATPL. Once he gains the required flight time, is ATPL will become "unfrozen".