Unless you're the person being shot by some rando & them doing so causes you to be dumped in the middle of nowhere in between the 2 jump points. Thus causing you & the ship you're on becoming stranded with no chance of retrieval. Personally, I'm hoping that this example is the reason why you won't be able to use weapons while jumping or in quantum, because the ability to do so would be a perfect opportunity for a sneaky troll hiding in a fleet to screw over the fleet by knocking some of them out of the group.