What you asked initially was "What if it turns out that she did kick him? Should she have been arrested if so?" That is a textbook example of a hypothetical, and, as I've said before, the only possible response to your first question is "Who knows?", and so the answer to the second is "Who can care, since we don't know the answer to the first question?" This is derailing, not in that it changes any direction in any meaningful way. Because it is hypothetical, it has no direction; a derailed train does not continue running down another track. It stops running.