It totally depends on the individual crayfish. I have seen many examples from the same species that were aggressive & placid. Its possible but to make a claim like that about all his crays I would say no. The only crays I would say that about would be dwarf crays.
Yeah, that was ME your talking about and you should have actually read what your talking about. They were dwarf crayfish, dwarfs aren't as aggressive, do more research before you laugh at others
Oh and they are not lobster...for the millionth time...lobsters= SALT water..crayfsih=freshwater, its frustrating seeing people make up stuff just to make extra sales on the same thing.
Environment can change behavior of animals significantly. I raise M. Rosenbergii Prawns. No, not crays, but stay with me here. M. Rosenbergii are widely known as the most agressive invert, at least in the hobby. Mine were raised since post larval with lots of food in a pool with guppies & snails. Unless the guppies or snails are sick, they don't hunt them. They have the good life and never need to hunt. The wild caught ones kill for sport and you'll never keep fish with them. Just a data point.
Another point, if you expect people to read & understand, you be dissapointed often.