I'm not sure why, but people seem to equate eating with health. I guess as products of western society, if we aren't eating, there must be something wrong. That isn't necessarily the case for predators and particularly not for predatory crustaceans like stomatopods. Large O. scyllarus will for for a week or two without feeding around the time of a molt and they will also often quite feeding when stressed such as happens when they are shipped or even moved from one tank to another. Some are so finicky that they will stop feeding for days when their diet is changed.
I'm not saying that this animal is healthy, just that whether it is eating is not a reliable indicator. By the way, $50 is a pretty healthy mark-up for even a large O. scyllarus. Admittedly you will pay close to that if you order one and pay shipping, but stores that received shipments of stock should be able to sell them for less.
Roy