Try giving the bass slack line about half way back to the boat when hooked on a multiple treble hook lure. If the hook goes through the basses jaw passed the barb, the hook will usually stay embedded. The bass can easily shake loose most hooks that don't penetrate beyond the barb.

I have found floating lures that bass have managed to free and had floated back up on the surface. Bottom line; some will die and most survive.

WRB

I have a small pair of wire cutters that I bring with me. if they get gut hooked and I cant get the hook out in the way they show in that link I reach in and cut the hook as far down as I can. it also works well when you have a treble hook stuck in there. its got to be easier to digest half a hook than the whole thing.

The fish was probably foul hooked in the butt.

Sorry man, absolutely NO WAY this fish was foul hooked. It was in his butt hole heading out. Unless he mysteriously sat on it then did a little shimmy to get around the barb. There is absolutely no way for a foul hook there.

I once caught a bass with about a foot of braid coming out of it's butt. Not as gruesome as your fish, but same idea

Man i have been doing things wrong all this time. I will usually cut the line at release the fish! THANKS GUYS

I caught a small bass once that had a hook poking out of the side of its gut. The point was rusted off but it was still lodged inside him. I fixed it.

The first year I fished Fork, I caught a 7 lber that had 3 existing hooking in its mouth.   All 3 had different lenghts of mono protruding from her mouth.

  All at different stages of eroding.

I do think old hooks and cheap hooks will rust eventually, but some of the new hooks on the market will take a lot longer than most expect.

I have been lucky to retrieve a few lures once lake levels have dropped after a year or more.     A year or more in the water and the hooks were on there way to rusting.    

     What happens to a human when you get a splinter, it festers and the body tries to break it down.

     I think what chemicals a bass has in its body would do the same, I just think hooks are not as cheap when most opinions on hooks left in the mouth would do are from the 70's and less quality hooks.