"What is the purpose of your visit to Israel"? should be a normal question going through customs. "Ramping riots & mayhem about your govs policies, Sir/Madam" should be a legal reason to disallow entrance, would it not? Instead why not cheer them, shake hands while thanking them and have them walk out frustrated and ridiculed.
Saudis warns U.S. that 9/11 responsibility law would erode investor confidence in America (Reuters)