They should have done their research before harassing this man. Ilhan is a proud Arab-American.
She was a keynote speaker at an Arab-American Day event in DC.
Ilhan only spoke at that conference and never once referred to herself as Arab (to my knowledge). This is almost the same as saying Somalia is an Arab country because we're a part of the Arab league and took part in several of it's congresses. You can show solidarity to a community (which will benefit us in the long run, or so we thought) without necessarily identifying with them.