In short, Heads in the Sand does not make a convincing defense of liberal internationalism. ~Austin Bramwell 
Mr. Bramwell’s dislike of foreign policy school labels makes this statement much less powerful than it could be, since presumably he doesn’t think that there is any argument that could credibly defend what he considers to be the foolishness of reducing all problems to a “single solution.” Bramwell writes:
The way of the distinguished commentator on foreign affairs is to reduce all problems to a single solution—realism, neoconservatism, internationalism, isolationism—while assuming that one’s opponents do the same.
But it isn’t as if realism employs a “single solution” to diverse problems, when it is arguably the most flexible and adaptable of all the “schools” in its willingness to use any number of different tools and institutional mechanisms to advance perceived national interests. What everyone can recognise as a shorthand for a series of complex arguments and assumptions about international relations is for Bramwell an exercise in simplification and a “lower level of mental performance.” Shorthand labels are useful in arguments, to the extent that they can sum up and define a position without having to restate the position and the objections to it. They can become substitutes for arguments and be reduced to epithets hurled with scorn (the inclusion of “isolationism” in Bramwell’s list is misleading, since such a thing doesn’t exist and the term has always been nothing more than an epithet from the beginning), but properly used they can be descriptive, clarifying and time-saving. The labels provide something like an ideal type that creates a standard against which one can measure the substance of a foreign policy proposal. Labels are signs that explain to the audience what it can expect and how it should read a text. They are a necessary and unavoidable part of any discussion, and they are not “simple solutions,” but rather pointers towards a series of discrete proposals and “solutions,” assuming that we want to adopt a liberal attitude towards these things and assume that international relations are filled with problems to be solved rather than realities to be managed.
In fact, the critique Bramwell makes of Yglesias’ book is a more or less realist critique of liberal internationalism from the right: states will act rationally in their perceived interest, multilateral institutions cannot constrain powerful state actors and so are largely irrelevant to the realities of international relations and even the “successful” multilateral institutions that seem to demonstrate the potential for collective security are chimeras. In short, Yglesias could not have made a successful defense of liberal internationalism that would satisfy Bramwell because Bramwell believes, as many right-leaning realists would, that international relations are governed by powerful state actors that use multilateral institutions only when it serves their interests and otherwise discard and violate the “norms” that are supposed to control state action. More to the point, Yglesias could not have made a successful defense of liberal internationalism because liberal internationalism is not a credible foreign policy vision, and Bramwell’s critique of it helps to explain why that is so.
More interesting to conservative readers might be Bramwell’s deployment of his notion of legitimacy  in the review:
In the face of such massive public ignorance, the Democrats probably could not have opposed the Iraq invasion and won. Voters do not pay close enough attention to politics to grasp the counterintuitive conclusion that the president wanted to invade a country that had not attacked us. Indeed, at the highest levels of wisdom, perhaps we should be grateful that the public never quite got it. Greater public awareness of the reasons, or lack thereof, behind the invasion could have sparked a crisis of legitimacy. It may be better to continue to waste lives and treasure in Iraq than to allow our institutions to come under fundamental attack. The people must not know the truth.
Goodness knows what goes on at the “highest levels of wisdom,” but I am certainly glad not to be at a place where I could make such a claim. This paragraph encapsulates far better than I ever could have in my earlier post why Bramwell’s definition of conservatism as the “defense of the legitimacy of institutions” is both basically wrong and profoundly irresponsible. This is a kind of legitimism that puts the welfare of the state ahead of the interests of the country and the people, and it assumes that corrupt institutions that usurp authority and violate the fundamental law of the land should be preserved as they are rather than come under fundamental attack. If I thought that this was what conservatism required, I could not be a conservative, since this would require me to betray my country for the sake of the state. Fortunately, I believe that this sort of legitimism has nothing to do with being a conservative.
Overlooked in this paragraph is the fact that most of the people today do know the truth that Hussein had no part in 9/11 and had no meaningful ties to Al Qaeda, and they know that they were consistently misinformed by the government with hints and claims to the contrary. There has been a crisis of legitimacy ever since the invasion, because the government acted illegally and dishonestly in launching the invasion. The proper response to government abuse is to root it out, not make excuses for it. Indeed, that is often the only way to preserve the legitimacy of our institutions and so preserve them from more radical and total rejection later on.