I have mixed feelings on this one. Let's look at this another way. Let's say you invited me over to your home, and you had a rule that no one could smoke inside your house. If I lit up a cigarette anyway because smoking is legal and I am free to do as I wish, am I making a stand for freedom, or am I just being rude by ignoring the rules and customs expected in my host's home?
I would strongly object to anyone expecting Michelle Obama or any other American woman to wear a headscarf when the King of Saudi Arabia visits the White House, or even if they were to hold a meeting in a non-Muslim country somewhere. But she was in their country as a guest. If she didn't like the expectation to wear a head scarf, she could have chosen to stay on the plane or just stay home in DC.
We are not talking about a requirement imposed on her, but about showing respect for your host country, an important aspect of international diplomacy. Her actions show a lack of maturity and a lack of understanding of understanding of her role as a representative of the USA at these types of diplomatic functions.
Point taken. But I don't think going bareheaded can be compared with smoking in someone's home. It won't make you sick.