I believe he knew exactly what he was doing. He had some very unappetizing photos taken of him a day or two earlier drenched by a rain shower. He wouldn’t allow that to happen again and by having the Marines hold the umbrellas he was advertising who is in charge.....him. Total narcissist.
The Marines know how to get their own back.
For eight years Clinton stepped off Marine One, took the Marine’s salute, and no one on his staff noticed that the Marine failed to face toward his back until he was out of sight.
Army officers in dress blues were ordered to carry canape trays for the assembled WH guests. Senior Army officers ordered to brief the CoC were ordered to report to the WH in civilian clothes.
Yes, a Marine may hold an umbrella for a woman. That must have made his onerous duty somewhat tolerable.