I have to agree with Brian on this one. F&$# the queen! It should be seen as the queen offending the US by expecting us to treat her as a “sovereign”.
She is a sovereign.. of England. That is why you don’t put your arm around her, unless you are the King of England.. but you also don’t bow to her, which citizens of England do. Barack Obama is the sovereign of the United States(voted into that position), Queen Elizabeth is sovereign of England(by bloodline). It is a meeting between sovereigns.