oh for goodness sake, it's a game, the rules alow you to change a ships heading, if that ship hasn't fired, their isn't a single thing in the rules that stops it firing at any alternate ship it can target.
yup intent is one thing, but you get the "rules as written" quoted often enough. It's no different than the accidental ass boresight, you didn't line it up on purpose, you didn't declare it, but, wait a minute, I AM lined up, wow, lets shoot...