I think you're right. She has the right to ware whatever cloths she like.
There is nothing wrong with her shorts. Its not like they are extremely short or showing anything. Anyone who is offended with her shorts have no life and need something to bark about.
Critics are raising the question whether it's appropriate for the first lady to wear shorts. Come on.
Her shorts are fine, people is so dumb. She's female, it's summer, she was a grand canyon tourist: get over it!