Well you are correct, you probably don't want to get bent 100 miles offshore, then again if those guys get a little bent, I would presume they are going (back) down with some oxygen.
My point is as follows.. In my opinion, there is a pretty wide variance in the ability of different people to offgas. There are obvious factors like age, cardiovascular efficiency/conditioning, how fat they are etc. If you are around serious scuba spearfisherman, you may find that they are doing some pretty aggressive profiles. Many times 3-6 hard dives per day. A good percentage of people would not be able to do this without getting hurt (I think). So the population of these divers is not representative of the general diving population and it self selects for "robustness". Even issues like sinus congestion and the need to clear your ears so many times, can become significant limitations for some people.
There is also the issue of PFO. Before you get your heart set on following this kind of aggressive activity, you might want to make sure you have what it takes (whatever the hell that is). I am being serious and I know it sounds macho, but there are divers who are not in great shape, not young and can seemingly push some pretty aggressive dives many times without getting hit. There are others (who may have a PFO) who clearly are more vulnerable.
I had a friend who used to get elbow hits pretty frequently, doing nothing stupider than the rest of us (and he was a jogger)... although it was in the forearm/elbow which he clutched his gun with on deco. We started doing deep stops and he started moving around a little on deco and seemed to avoid those, somewhat frequent minor hits.
I've been bent a little a few times myself ( I think). Spearfishing is such a unique activity and technical spearfishing is even more unusual, so I am not so sure the normal tech diving lessons are the best. I personally have zero tech training, but have been around spearfishing for a long time. In my opinion, you will be best served by diving with good spearos, for a while in progressively more challenging sites rather than immediately taking a a loooong string of technical classes.
FYI Chad Carney lives on the east coast now, not sure if he is still active in teaching technical spearfishing, but he would be a good person to talk to about your goals. He is a nice guy and a good diver, although I personally have only been snorkeling with him.
Lastly, the guy who just gave that talk is NOT normal. Sorta like going to hear a world record holder in ultra marathon running or something, and deciding you want to do the same thing, when the furthest you have jogged is twice around the block.