I've had a few cool cans over the years on cars with a carb. Look inside...they all had copper lines. Same with some of the
oil coolers and trans coolers. All aftermarket units admittedly, but the factory wouldn't spend the extra money on a copper unit anyhow.
I guess if you are worried about the copper lines, you should be worried about the copper wires running right next to it. I would hate to see those corrode and cause an electrical fire. I would assume they would fail a lot faster since the wires are so small.