He catches that she says his name easily—his name being Voldemort. Harry's somewhat surprised about that, because he comes to the conclusion that it was Draco who led to that. But still, her statement is a little strange for him. From his perspective, he can't be here—and he's more than willing to tell her that.

"He can't," he begins. "Voldemort. He can't come here. He's gone for good." And getting a third shot doesn't exactly seem likely after all that. There might be other Dark Lords, to be certain, but no Voldemort, not anymore. After all, he was hardly the first.

He realizes he doesn't comment on the victory, but then again, he's commenting on a victory of his own. That's enough.