There is one very important thing to remember if being targeted by the submarine community: They are very proud that they are an "all volunteer force". So, what they are looking for in these interviews with unwilling midshipmen is a change-of-heart or ambivalence.
Example of ambivalence: They will start off by flattering the targeted midshipman. "We have looked over your record and, whether you realize it or not, you are ideally suited for the submarine community. You're exactly what we're looking for. We can see that you will excel in the submarine community - even if you're not fully aware of it. There are over 70 years of submarine experience in this room and we know the real deal when we see it ... We notice that you have subs as your 2nd choice. How strongly do you feel about that? Can you even conceive of serving in the submarine community?"
If the midshipman says something like this - he's toast. "Well, I enjoyed my submarine experience during Protramid - and it was a tough decision to decide to go air over subs. They are both excellent communities in which I would be proud to serve."
Bingo! Music to their ears. Unwittingly, this midshipman basically said, "My first and second choice are equal" - at least, that's the way they'll interpret it. So, assigning this midshipman his second choice is not "forcing" him. He just volunteered! After all, didn't he just equate his top two choices?
The key is to make it clear that your choices are your choices. The academy asked him to make a preference list and he did. They are in the order of preference. This has to be conveyed assertively and respectively. They will shutter when the midshipman says things like, "I would be lying to you if I said that my preferences are anything other than what they are." If pressured even further, they will again shutter if the midshipman says, "If ordered into submarines, I will say 'aye, aye, sir' and do my best - but it is not my first choice."
The midshipman can also say something like, "You say I would be perfect for submarines by looking at the papers before you that likely address the courses I took, the grades I received in those courses, and other things like my military aptitude. What's not on those papers is what is in my heart - where my passion lies - what excites me about my future in the Navy. I have been asked to convey my preferences based on my exposure to and education of various communities during my years here at the academy. My preferences are what they are. My first choice is my first choice. My second choice is my second choice. I'm not confused nor ambivalent about that order."
Never forget that you are not the only one being targeted to fill the submarine quota. Don't be the slowest running antelope. The hyena usually catches the slowest running antelope. Just run away faster - but respectfully.
(This is the Reader's Digest version)