as far as i know Copay is just a wallet and it has nothing to do with their "merchant interface" options. and this wallet added support for Bitcoin Cash. and that has been because the users who are either using Copay or those who are supporting BCH have been spamming them for support of this coin.
so far i have not seen any merchants though.
if they start then that will be worth mentioning because it will be big.
That's right, there are basically no merchants for Bitcoin Cash, that's why nobody is using it. There is close-to-zero transactions on the BCH network and probably the only ones who are buying it are speculators who are after quick bucks.