That's very disappointing.
I don't do much fishing in deep water, so my experience with the bladder-puncture technique is very limited. A friend has done it many times, mostly on Walleye and Whitefish brought up quickly from deep water. It definitely can work, but even with much experience he doesn't always get the spot perfectly. He doesn't go in at such a shallow angle, rather prefers to be much closer to perpendicular to the body of the fish. Looking at the anatomy of a healthy fish gives one a knowledge of the location of the swim bladder, but when it expands out of control it also extends much further backward and fishermen who are proficient in this technique seem to aim for that rearward extension a bit?
For us as fishermen, when it "works" the fish is released and disappears, so I have no idea what the long-term effects are. If the fish is able to dive down on its own, we think we are "successful"...but how does the fish fare in the coming hours/days/weeks? It's actually one of my main reasons for not fishing deep, unless I plan to eat the fish (which isn't really that often). I release fish carefully, don't just toss them back willy-nilly, so I don't like to see them struggling on the surface.
When I took the required CPR courses to maintain my eligibility to work on large construction sites, it was always explained to us that CPR was a last resort that only rarely saved the patient. I have the same suspicion about this technique, although I certainly can't prove or disprove it.