"Are conservatives seriously going to argue that she knows what she's talking about?"
Phil, anybody who cares whether Palin can give an exegesis of the Bush Doctrine is already committed one way or another in this election. We're at the point of the campaign where all that matters is the opinion of undecided swing voters -- whom surveys consistently show to be the least-informed, least-engaged segment of the electorate.
Talk to these people, and you will consistently hear the same phrase repeated in various iterations: "I don't vote for the party, I vote for the man." The independent voter believes himself capable of making a "gut hunch" assessment of a candidate's character and ability. The independent vote is non-ideological and non-partisan, and is prone to bandwagon psychology. The independent voter disdains "politicians," and is a sucker for anti-politicians like Ross Perot, Jesse Ventura and Arnold Schwarzenegger.
To say to the independent voter that Palin is not a foreign-policy expert is in fact to endorse her, since the independent voter hates those snooty know-it-all "experts" and believes that foreign policy (like all policy) should be based on "common sense."
These typical attitudes of independent voters are the "is" reality, not the "ought" ideal, of American politics.