Head gasket- Why not Penetrox?

[P.S.]

Please don't laugh at me, I am still trying to learn here.

So, when using the copper style head gaskets, I see in previous threads recommendations from copper coat to grease and everything in between. Most of the knowledgeable people seem to recommend the copper coat spray.

In my line of work (radio communications and engineering), whenever we have dissimilar metals in contact with each other, especially in the presence of moisture, we use Penetrox on the joints. It's like a zinc grease that keeps the dissimilar metals from reacting.

So....

Since a Model A motor and head are both cast iron, and the head gasket is copper, why wouldn't we use Penetrox or a similar product? Or, am I reading too much into this? Is there no problem with the copper sandwiched between the cast iron block and head?