This explanation makes sense, especially considering that Obama that is a superb strategist. Maybe he’s trying to neutralize the Religious Right.
I think this is a matter of Team Obama kicking the ball downfield on the first down to wait and see whether Team Evangelist will fumble it. Obama offers Warren the chance to kiss the ring and come on board, and if Warren shoots his mouth on at the wrong time he relegates his team to the bench in the eyes of the American people (how were those last sentences for literary clichés?). If Warren plays along then Obama can continue his post-partisan policy-making without the direct opposition (an tacit support) of the evangelical movement that has so infected American politics.
Pragmatism, Machiavelli-style.
Choosing the lessor of evils is never-the-less choosing evil.
On the other hand, transforming evil to good is better even than defeating it. Not saying that’s what’ll happen, but without engagement it’s not even possible.