Why is he doing this?
1. It gives each network something unique of its own to show on the night before Obama does his live address, so maybe this was part of a deal to insure that they'd all preempt regular programming for the live address.
2. It acknowledges our skepticism not only about Syria but about the journalists who have coddled and promoted him to us for so many years. Putting them in competition with each other creates an incentive for somebody not to be a lackey.
3. It makes him look strong, alert, and vital in the midst of many observations that Obama looks tired and weak.
4. If he's so vigorous and ready to go to war, maybe Americans who say we're tired of war will rouse ourselves.
5. We're not just tired of war, we're tired of those damned journalists, but isn't there one person on that list of 6 that you're not tired of?
6. At least you can't accuse him of dodging the tough questioner on some other network. He's submitting to Fox too. (But Chris Wallace is kind of a sweetheart. Look at him here.)
ADDED: It's also possible that Obama, knowing the vote on Syria is already lost, is using the occasion to set up the congressional vote so that it will work to the best advantage of Democrats in the 2014 elections.