"Buying, selling, or transporting protected wildlife, mussels and fishes, raw fur, or processed wildlife."
Processed wildlife, is what got them as it doesn't imply any protected species. It doesn't say Processed protected wildlife just processed wildlife (mounts, sheds, turkey feather displays, all that junk). Most of us know this law but non-hunters/fishers could very well not. Doesn't excuse the crime any though. If you get pulled over for speeding, saying "I didn't know the speed limit" doesn't matter, it's still your fault.
And yes that law was written in the '50s but it was updated in 2006. So the antiquated law defense shouldn't work.