Well, yes, I think he is using metaphor, Jack.

He says: "my latest book on how America rules its Mideast empire"

He can't mean it literally, because there is no officially established American Empire in the literal sense, so he means it metaphorically. I've read some of Margolis' books, and I know he means it metaphorically.

Americans grow up in a society that claims not just to stand for freedom...but seems to also pretty much assert that it invented freedom! ;-) Given that mental conditioning for Americans from the youngest age, their government can hardly go out into the world and establish official colonies and an official empire. It wouldn't look good. So other means are found of doing it, and those other means take a variety of forms.

Be that as it may, America has established indirect control over virtually all of the Middle East and North Africa and central Asia, with the exception of Iran, which is why America is so bent on somehow "taking out" Iran and achieving regime change there. Iran is like the one store left in Al Capone's city which hasn't been frightened into paying for "protection", thus they are potentially under the American gun at all times. Only the sheer cost and risk of engaging in a war with Iran has saved them thus far, given that the USA has its hands very full already with 2 military occupations in Muslim lands and a financial crisis at home. Fighting Iran is an expense the USA can't afford at present. (but the same excuse for doing it as was used for Iraq is being held at the ready: rumors of alleged WMDs).

America has (with Israel as a partner) established an unchallenged sphere of influence over the entire Middle East with the exception of Iran. That is the "American Raj" which Margolis is referring to. It is an empire, for all commercial purposes, but it's not an official empire. There aren't really any official empires in the world anymore, just some unofficial ones. China's unofficial empire, for example, extends into Tibet, and I believe they're pretty cosy with North Korea and Myanmar too.