I sort of agree with you; in my opinion, a Secret Service agent should have KNOWN the procedure and should have been prepared. It's his duty to help the pilot faciliate HIS own boarding.
It sounds like HE is too sensitive about his ethnicity. And it sounds VERY stupid to have carried that book onboard for all the rest of the passengers to see. Would you do that?
The book was not visible to other passengers. The flight attendent found it upon searching his carryon materials. The person sitting next to him who would presumably be the only person able to see what he was reading it, was not offended or excited by it. He is one of the witnesses that has come forward for the agent. Yes a college level history of the middle east is really scaryyyyyyy. BOOOOOOO. Did I scare you?