It's probably fine for simulations, but biometrics could go all over the place depending on what's happening in the pilot's life. With a yoke, if you're mind wanders onto worrying about if you're mum's going to be all right in that operation, the yoke stays where you put it. But an brain scan will measure tension and react. Unless it can actually read thoughts rather than measure activity, it'll be unable to distinguish between different intentions and ordinary thoughts.
Games ought not to suffer from that as the games are, supposed to be, fully engrossing. Although the moment the phone rings or there's a knock on the door, or you start worrying about finishing that homework that you keep putting off, the player character might start behaving pretty oddly!
We gamers get little enough exercise as it is.
