Early in my fisheries career I was part of the group that managed the coastal crab fishery. What Smalma posted is what enforcement used on the commercial fleet, the recreational fishermen, and the processors. When you get a real hard shell crab, I preferred barnacles and color on the shell to judge, you will see a big difference in how much meat you get.
The reason they can’t sell them is because the processors besides it being illegal, don’t get the meat recovery they need to stay in business.
Even if they are commercial fishermen, they can not keep more crabs than a recreational limit.