Logical Thinking
He knew that he was going against direct orders, so he was hesitant to leave instructions to his colleagues for fear of being punished. He figured if he did get caught and ended up being imprisoned himself, at least he could give his wife the details she needed to find him.
She was the only one who could decipher his message and send help that might save him the punishment he’d surely face for disobeying orders from his commanders.