Not an unreasonable assumption, but given the fact that he spent most of his time in solitary, that is somewhat irrelevant, don't you think? A list of co-prisoners would be helpful.
It is just an assumption. I don’t have a huge investment in it.
However, he was the son of the chief naval guy in the Pacific, Admiral McCain. That wouldn’t have made him commander, but it would have had eyes on him among his fellow prisoners.