Because he’s one of the few, if not the only, in either party with the cojones to write this:

Generations of conservatives followed the great advice of our Founding Fathers and pursued a restrained foreign policy that rebuffed entangling alliances and advised America, in the words of John Quincy Adams, not to “go abroad looking for dragons to slay.”  …

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Neoconservatives who have come to power in both the Democratic and Republican parties argue that the U.S. must ether confront every evil in every corner of the globe or risk danger at home. We need to “fight them over there” they say, so we don’t have to “fight them over here.” This argument presents a false choice. We do not have to pick between interventionism and vulnerability. The complexity of our world is exactly why the lessons of our past should ring true and demand a return to a traditional, pro-American foreign policy: one of nonintervention.

Read his five principles. I’d argue with #1 - in that working with multinational organizations can strengthen everyone. But #2 and #5, in particular, are right on.