Not only that, Philip. Contra Ackerman, the case for democracy promotion is not limited to the narrow question of what kind of states directly sponsor terrorism. It also extends to the American interest in reform of the sorts of repressive political environments where radicalism is likely to arise.
By the way, it's quite odd that Ackerman thinks it's really signficant that Kaplan's piece doesn't contain the word "al-Qaeda." Kaplan's reference to democracies' "thin history of exporting terrorism" very obviously does allude to al-Qaeda and similar groups.