If he settles on something else for less of a wait time, I can almost guarantee this will not be his life's career. He will not be satisfied, he will not be happy. Nothing is more of a deterent to joy than being miserable all day at work. I know waiting isn't easy. Anything worth having, is worth waiting (working) for. Please tell him to REALLY REALLY REALLY weigh his options. Tell him to sit down and have a very candid conversation with his 1st class or his Chief or even an Ensign or JG in his chain of command. Not a complaint session, not something that would be described as "jumping the chain of command" just a conversation, Coastie to Coastie just getting opinions, ideas, suggestions. I know Jimmy would talk to anyone about career choices and paths, Colin has gone to his Chief, an LT on his ship, he has played Wii with an Ensign, all the while talking to them, feeding off their energy, advice, passions... Nothing at all wrong with that.
I wish you both the best of luck and patience!