I sometimes don't know if you are "having fun" or not, David but will assume that you are for the sake of this conversation...
I was a junior high school teacher and since then, studied in an education PhD program with some people who were very clever about the sociological implications of policy - particularly the role of symbolism and language as it relates to issues, positions, and power.
When a kid would ask me, "Is it OK if I...?" my experience - often painfully gained - taught me to address the issues underlying the question or answer the question that was implicit in the words being chosen for my consumption.
My more recent work only reinforces my belief that we choose language purposefully so you can expect me to think that title was NOT incidental: It matters to the discussion.
If the real issue at hand was the part of the interior that can be replaced by .060 aluminum, why choose the word "gutting" in the title? It might be that RR's use of the term is conconsistent with commonly held definition of the term but if this is NOT the case, and someone here answers "yes," that might well be taken as inaccurate advice that it is acceptable to cut metal in the door structure.
What does "door panel" mean in the question in the body of the post? Just the door "card?" The inside surface of the structure? Something else? We don't know and before anyone points out that my question is both pedantic AND semantic pick and read ANY question about rules from this forum: They are ALL about semantics.
K