Correct, by law he was deemed to be in control of the vehicle. However, you can't prosecute someone for speeding when they weren't driving.
Drunk in charge? Possibly, but they have no idea how much he'd drunk and he might say he was just being cautious after having half a shandy. It's impossible to prosecute beyond reasonable doubt.
So I say again, would you be happy to be banned from driving in the same circumstances?