Perhaps if you spent some time in other countries, you might not be so cynical.
Many (not just one guy) do take the oath of office on the Koran where I live.
One rep doing that in the U.S. is just an exercise of the First Amendment.
I beg to differ-
1.There have been more than 'just one rep' that has done this. A judge in NC has allowed witnesses to swear an oath on this book. M. Osman Siddique, the first Muslim ambassador in U.S. history, was sworn in on a Koran in 1999, when he became U.S. Ambassador to the Fiji Islands, and I seem to recall a CA rep doing the same thing.
2.You may want to call it freedom of speech, but I prefer to call it spitting in the face of American culture.