"Of course we need secrecy. Why on earth would we not?" Muggleborns were one thing, but they were still wizards. He had absolutely no interest in anything in the muggle world, except maybe access to some of their food when they ran out.
"Believe it or not father, we can have a new, better world and still be wizards. We'll just be wizards who don't murder each other. I'll tell Harry what you said, I'm sure he'll find something for you to do."
He stood and walked off, not trusting himself not to say anything worse.