'The salute is referred to as a "military courtesy." Reagan's return of the salute acknowledged and returned that courtesy; I saw it as an indication of the respect he held for our military and those of us serving in it.'
While I think it was clearly a matter of respect on President Reagan's part I'd still suggest it would be better if our civilian Commander in Chief did not salute. I always thought it was a privilege reserved for the military.
Indeed it is prescribed for the military. Reserved to the military? I have never read or heard that from any published guidance on the matter.