I think so too, it may be because it is a juvenile or its diet made it so that they aren't as bright.
Also, from what I have read on KP Aquatics, they sometimes catch emerald crabs that are much hairier than normal emerald crabs - so something similar might be going on with your ruby crab? I haven't seen any literature with pictures identifying a separate species that look like the ones that they sell. Crab taxonomy hasn't really been updated much during this century.
Hopefully we see him again this week, I am going to take a macro lens and try to get a better picture. The only thing different, or appears to differ is the claws. It could be because he is juvenile but his claws look shorter than mithraculus forceps.