Should I care that Obama is bowing down to the Saudi king? Why should I? Certainly it is not that he is showing where his "true allegiances" lie.
For the sake of comparison, here is Obama wearing a kippah at the kotel, which some crazies undoubtedly took to show that he is a secret Jew (just as when Bush wore a kippah), or to show his allegiances.
And here is Bush holding hands with a Saudi prince.
People do strange things in the name of protocol. And if it is indeed so that the American president need not, and should not, bow to a monarch, then at the most it is indicative of Obama's lack of foreign policy experience.
Furthermore, from the looks of the video, it is not a bow as in showing that one is a servant of another. Rather, it is more of a bow of greeting that normal people do towards one another in Islamic countries. He does it while shaking the fellow's hand. For more information, see the definition of salaam (equivalent of "shalom").
Give the guy a break!