Probably the mission would fail and the controller would coment "gratz you just made the Matrix collapse and destroyed the story continuity - mission failed, start again"
On a serious note - I've never really delved into the symbolical/philosophical/referential aspects of the Matrix franchise, and I'm not that adept in philosophy (not at all, actually).
But the way I've always understood this "you're here to understand why you made the choice" part is that every choice for every situation is pre-made by the person, and as soon the person experiences and "understands" all the reasons that influence this choice, he "actually makes" it, consciously.
So, in this case, Neo has made the choice to save Morpheus or Trinity long before it comes that far, or rather, it's the only choice he'd ever make if it came to such a situation (and it will come to this because others' choices are premade, aswell), and when faced with the situation, he perceives and understands what's going on around him, all the arguments for and against each choice, and then chooses.
If all choices ever made by anyone are all predestined and somehow found in the person('s brain?), that's how the Oracle could foresee everything - being able to calculate each physical chain of reactions and every person's action - unless she doesn't see through a part, and thus "can't see beyond choices she doesn't understand".
So anyway, it turns out that this is a direct reference to some quote that means something totally different. The "choice he's already made" was taking the red pill, the "liberation".
One can't ignore such an obvious reference, but also not the fact that it starts of the choice of taking candy (looking away from it being a possible reference to the red pill - something I didn't think about previously) right here, right now.
So anyways, was I completely wrong, or was my "interpretation" somehow correct?
