Only for certain game types: even Lightning -> HDMI has a slight lag, and AirPlay (AppleTV) has even more (seems to vary depending on the type of action being transmitted). Fine for racing in my view, and puzzles and strategy... not so good for twitch shooters or ultra-precise platformers. (Although the game parameters could be tweaked to help hide the lag for some actions.)
I love gaming from iOS to TV, and would love a controller, but I'm realistic about the limitations. iOS is best on its own screen. (Which would make portable controllers for iPhone/iPad Mini very tempting.)
He was saying that he wanted apps on his Apple TV, not that he wanted more games to be AirPlay enabled.
They could easily make the controllers work, with no lag, for Apple TV the same way they're going to do with iOS (mobile) devices: by using bluetooth.