Without adding 20 pages of diatribe, the short, quick and inadequate answer is...
Spearo's are lumped in with recreational fishermen. Right or wrong (for many reasons) that's how it is. Recreational fishermen take about 49% of the recreational catch, with 51% going to headboat/charterboats, which are also considered recreational except by me. Commercial fishermen take about 50% of the TAC (total allowable catch) for red snapper, and rec's take the balance. Whenever there is a ban on fishing, Recreational fishermen take it in the shorts, because the commercial guys whine cry and carry on that their "way of life and making a living" is being destroyed. Welcome to the club, everyone's way of making a living is being destroyed.
Anyway, when NMFS determines that a species is overfished, somebody is taking it in the pooper. Even though recreational fishermen add far more to the economy in terms of buying boats, gear, licenses, fishing vacations, etc. etc., they don't feed their families with the cash proceeds of their catch, so they don't make nearly as good channel 6 news coverage as the big nasty federal government putting some commercial guy out of business.
There are so few spearo's, their detrimental effects on the fishery overall are likely to be negligable. Most of the spearos that I know shoot a fish for dinner, then come home. They don't shoot turtles (one of the long line commercial by-catch problems), they rarely shoot undersized fish (and when they do, they tend to eat them anyway), what they shoot, they tend to kill (how about hauling a snapper up from 200 feet with a rod and reel, and throwing it back. How long you think that fish will live), and they dive often. Recreational spearfishing regulations aren't fair, but it is what it is.
There is really way more to the story than that. What I wrote is way oversimplified, and full of my opinion. If you want a diatribe, read some of the info on spearboard.com and spearfishingplanet.com. Try not to get buried in the hate.
Frank