I thought that is what was happening in the given situation, wedge with a TL on the TIE (if he wants it)? Making the situation analogous to declaring a BR and discovering that doesn't take you out of arc like you thought. You can't back up and focus instead.
None of the commitments force you to pick a different target if your original effort fails. If you try and lock A but find you're out of range, you can choose to focus. The question is how that applies to nested situations, but there's no other scenario in the game where if you try and do something but fail you're forced to try that same thing against a different target.
