Electrical and plumbing dielectric myth or fact
The metal / copper can create a problem. I have not found the insulation to be damaged but have found the points of contact created holes in the copper pipe and rusty spots on the metal. The pipe had failed in multiple locations under the house and the copper had to be replaced but the MC was ok even though water had been spraying on it.  I have seen several times when copper to galvinised pipe were made a metal union (it should a dielectric union) the pipes failed in a short number of years / months. I believe there is a photo on this site where chicken wire was used to hold up insulation and the wire was in contact with the Copper pipe and that pipe had started to fail. Not a myth copper and other metals can cause pipe failure, but I have not seen the insulation damaged.