Thought provoking points!

neither choice is morally obligatory

Moral requirements, I feel, change from culture to culture. Although I believe that there is a universal moral law, I don't believe that we've been able to agree on it yet (and I don't know what it is myself). I think the only way we can find it is through continual discussion and reflection like this.

self-defense/assisted self-defense

I haven't thought of it in this light before. Although I feel like there are situation that would require one "demand" that someone else self-sacrifice, I would also agree that self-sacrifice is a decision that you can't make for another person (you can sacrifice them, but self-sacrifice is ultimately their decision).

I would be interested to see how a judge would preside over a case with a similar situation. Good thoughts!