Oversimplify the situation, that always wins an argument. Tony couldn't even respond to the challenge-- it wasn't worth a response. If his father was a genocidal megalomaniac who had abused and controlled him all his life? And he had grown enough to start to realize that this was not okay; enough to send his sister away to protect her? Yeah, maybe he would like to get a few good ones in. But then, Tony never was really good at the family ties stuff.
At least the kid had some concept of reality, though; in Tony's opinion, the decision to allow Wanda to become an Avenger was a poorly calculated one. If he had been on the team then, he would have walked away. The Avengers welcomed former enemies to their ranks far too easily; like they wanted to be eaten from the inside out. Not that some of these reformers hadn't turned out to be spectacular teammates, and Tony recognized as well as anyone that people dealing with superpowers needed a little more give, but the screening process sure was lacking. It had tangled them in this strange web, after all.
"You would come now?" was all Iron Man asked, not particularly surprised at the conflicting messages. I couldn't come, Daddy would be mad, argue argue, but also I might just because-- Quicksilver's head was obviously a mess, Iron Man didn't need to call him out on that. That he did consider leaving the ranks of the Brotherhood with his sister, that was something the Avengers would eat right up. Maybe Wanda did have a point there-- remorse meant amnesty to them.