Just don't let it go too long, or it will pick up metallic off-flavors. I'd keep a really close eye on it.
Yeah, I was always under the impression that due to low pH of beer that copper was only safe on the wort side, but Palmer says "Copper is relatively inert to both wort and beer. " from the link posted above. Still, I'm not going to take any chances. I'm aiming for short exposure.
Also, FWIW I think the mineral stripped for copper for yeast health is zinc, IIRC. There might be other trace elements as well.