Suggesting you can win a war with just air power is a basically flawed idea. You can bomb all you like but you will never 'connect' with the people you seek to subdue in anything other than a kinetic way. Yes, you may make short term gains but you won't achieve the long term objective. for that, you need boots on the ground and he is correct.
The problem with Afghanistan is that nobody knew/could define or more importantly agree on what the final objective is/was.