You shoot fish, Jewfish decides he wants it, he grabs it after you have strung it, you now have a fish that outweighs you 2:1 to 4:1 dragging you around while trying to eat the contents of the stringer.
You can't release it because of the tension on the snap (a good reason to have a cut-awayable line on there!)
Or worse, he grabs YOU.
We haven't had trouble with them getting that aggressive around here - at least not yet. Sharks, yes occasionally, but not the Jewfish - yet anyway.
I HAVE seen them up VERY close (as in less than 5') recently though, and if he wants to grab you, you've got a major problem. They don't have teeth like a shark, but they do have BIG jaws, and they can clamp down on your pretty hard I'd bet. You ain't gonna outswim him, and you also ain't gonna just ask nicely for him to let go either.
They are vacuum cleaners though too. One wreck that I like to dive recently had one show up. The fish population has definitely taken a turn for the worse over the last few weeks - what was a huge (300') barge teeming with life now has a few short fish on it and one huge Jewfish..... if we dive there now, its to see him, not to spear any more - there's nothing legal to spear left there as he has eaten it all already.