I agree with that too. I said common but was too lazy to qualify it. I've seen them at least a few dozen times offered for sale at LFSs and on line in the last 5 years. So not too common, not too rare but closer to rare, I'd agree.
It is mass produced though for food in SA. The demand must be not great for it in the ornamental fish trade, just like for its a bit more common and famous cousin TSNxRTC.