I seem to recall Eisenhower and other presidents up to Reagan never RETURNING a military salute. Eisenhower was a real general and understood and valued military protocol and, although he was the Commander in Chief, he was a civilian as proscribed by the Constitution. And civilians do not return a military salute.
I loved Reagan but he started a bad tradition.
I can’t resist telling you a little story that I’ve just told the Marine guard at the embassy. The story has to do with saluting. I was a second lieutenant of horse cavalry back in the World War II days. As I told the admiral, I wound up flying a desk for the Army Air Force. And so, I know all the rules about not saluting in civilian clothes and so forth, and when you should or shouldn’t. But then when I got this job and I would be approaching Air Force One or Marine One and those Marines would come to a salute and I — knowing that I am in civilian clothes — I would nod and say hello and think they could drop their hand, and they wouldn’t. They just stood there. So, one night over at the commandant’s quarters, Marine commandant’s quarters in Washington, and I was getting a couple of highballs, and I didn’t know what to do with them. So, I said to the commandant — I said, “Look, I know all the rules about saluting in civilian clothes and all, but if I am the commander in chief, there ought to be a regulation that would permit me to return a salute.” And I heard some words of wisdom. He said, “I think if you did, no one would say anything”.......Ronald Reagan 1986
https://taskandpurpose.com/mandatory-fun/vice-president-kamala-harris-salute/
I am ambivalent if the CIC was prior service. Jerks like klintoon, barry and the current resident never rated a salute because they never served.