Ok, i think i know why this card is worded the way it is. So many people seem to be going back and forth, but sometimes each individual/play group cultivates a method of playing a game in such a way that they are all unaware they're breaking a rule or not following a procedure. SO, here goes my attempt to penetrate the veil.
It says choose a ship. I have commonly observed people measuring the board wide, looking for the best targets to attack or declare actions against. Same when people boost or barrel roll. However, as per tournament technicalities, you cannot pre-measure anything. So the card says "Choose a ship". At this point, you're eyeballing it and hoping you're in 1-2.
Then you measure, since now you have declared your action. If this was an ordinary target lock, you'd be checking to see if it's within 1-3. If it is, then you acquire your target lock. However, if you are not within range 1-2, and not in it's firing arc, then by merit if the rules, you cannot even finish this action because the target isn't legal. Remember, you don't resolve this action in small parts. For instance, if a player were to use Expert Handling, but had no legal space to barrel roll into, they would not get to resolve the rest of it and shed their target lock. So, if you were to choose an illegal target, then this action fails to resolve and you could either choose a new target, or a completely new action. This is how any conditional actions are resolved in this game.
So just to be clear, lets look at action resolution again.
1. declare action.
2. check to see if action is legal.
3. if it is legal, resolve. if not, choose a new target or a new action.
OR AT LEAST THAT'S WHAT I WOULD HAVE TYPED IF THE POST I WAS LOOKING AT HAD THE CORRECT CARD TEXT.
So lets apply my previous logic to the real text.
Choose an enemy ship at range 1-2. If you are within that ships firing arc, you may acquire a free target lock. Then, you may perform a free boost action.
Okay, so, lets choose our ship. Okay, that guy. Are we within his firing arc? No. Boo, no acquiring a target lock. Okay, now i can boost.
Note that in the correct text of the card, the only thing conditional in this text is the acquisition of the target lock.
However, one should note that following proper resolution steps, if after choosing your ship you measure the distance and you aren't within range 1-2, then none of the action is legal and you must choose a different ship (or a different action).