Because Putin recognizes Obama hates the West more than he does.
But it is not about Obama. NATO will handle it as a European crisis and ask Obama of nothing, because they know he is useless for any endeavor.
You know these things with bright colored wires and wooden blocks sliding on them? You find them in pediatric offices. In NATO they have one, so when Obama shows up they set him in front of it. Obama practices hand to eye coordination, and they can talk in peace.