As someone who has made the announcement during a full honors wreath laying ceremony...the instructions are very clear...you are to remain "silent and STANDING" during the ceremony.
People are there not only to watch the changing of the guard ceremony, they are there to see a very hallowed spot in U.S. military history, the Tomb of The Unknown Soldier...and to pay their respects to the nameless soul who made the ultimate sacrifice for their country. It's not a place to make some vapid meaningless political statement.
The coward in the photo didn't even have the guts to do his little moronic knee bending stunt where everyone could see him. He's off to the left...behind the chains and partially blocked by the warming shack. If he'd been in plain view...the civilian security guards would have tossed his sorry @ss out of the cemetery.