Not likely that this was an O. scyllarus. However, this time of year there are a lot of Hemisquilla ensigera being taken by shrimpers and halibut fishermen of southern California. Its there breeding season and they are caught away from their burrows. Several outlets have been selling them. These guys can get much larger than O. scyllarus, up to a foot long.
I certainly have nothing against eating stomatopods. The originally scampi may well have been Squilla mantis and you can find it in most seafood restaurants in Venice. A few years back at the first ever and only world stomatopod congress in Trieste, the organizers cooked up 125 lbs of Squilla (garlic, butter, pepper and parsley) for the main course and the finishing banquet. Throughout the Indo-Pacific you can buy Lysiosquillina maculata - often at unreal prices. I have seen large ones in Tahiti go for $75. In Thailand, Harpiosquilla females are grilled on sticks, frying in the oil from their ovaries. Males aren't considered worth eating. I think the only time I was really put off by being served mantis shrimp was in Indonesia when we were given a huge platter of freshly steamed O. sycllarus. Oh, and there is the fishing village in Japan that serves a breakfast bun with a freshly molted squillid cooked inside.
Roy