Now that I think about it, it's odd that he stated that with such certainty. It's not like Voldemort or Dumbledore used that strategy - maybe he's thinking of Grindelwald? Apparently his motto was "for the greater good"...

Yet that's not exactly what happened as a result of Harry's actions. The "afterword" of the trial suggests that any members of Lucius' faction who follow story-book logic will see Harry as a dangerous enemy, as will members of Dumbledore's faction who have "walked the path of a powerful wizard."

Though that actually raises an interesting question--what happens when, say, Alastor Moody goes to Dumbledore and says, "Albus, I think Harry is Voldemort"? Does Dumbledore tell Alastor he's wrong, and convince Alastor that there is a better explanation for Harry's actions? Or does Dumbledore say, "dear God, Alastor, you're right!"

On a related note, what does Dumbledore know about horcruxes? Dumbledore's dialog has suggested that Voldemort may have gone around destroying a lot of information on horcruxes, so Dumbledore may know less in this story than he did in canon. Hmmm...

EDIT: See also JenniferRM's comment below.