You won't get hammered from me. Copperbands are a fish that should never be quarantined, especially in a small tank and those sores are actually caused by copper. Antibiotics will probably make it worse and I would be very surprised if that poor fish is still alive.
IMO, if you are of the mindset that you have to quarantine, don't get a copperband.
I can see a fresh water dip for 3 minutes as they do carry a lot of flukes, but thats about it.
Copperbands are long lived fairly robust fish as long as they are treated in a way that does not stress them to much. They need a lot of hiding places in a proper tank, not a bare or semi bare small tank. I am sure the vast majority of them kept in such conditions die because of that and not disease.
Just my opinion of course but I have almost always had one in my tank since the 70s.