The neat thing about being the C/E on a '95 cutter that had two docks full of commercial dungeness/salmon boats adjacent to us was that we got to be friends with some of the owner-captains and fishing crews.
First off, most of them don't really eat that much crab. They've been doing this for years and they're sick of the stuff. Once in awhile, yes, but not as often as you might think. They all pretty much say the same thing, that when they stared out in that line of work, they ate it, after the first year or so, they were so sick of it they wouldn't touch it for ages, then after that they would only eat it occationally.
The other thing they all said was that you _don't_ eat sellable product, and yes, the bulk of the undersize ones and females do get thrown back, but guess what goes in the pot when they want a crab dinner? Something that they aren't loosing any money on.
As for the Alaskan fisheries boats that handle king crab, these are much bigger vessels, that haul in much larger catches, so maybe no one is going to miss a few adult male crabs at the end of the day, but on the dungeness boats, you can bet your ass that no one is going to eat profits.