The approval numbers are relevent I suppose, but of all the hypothetical candidates Kos chose to spend money polling against Obama they decided on.....Trump? 
Donald Trump came onto the scene very fast and very loud.
He quickly became a me-too Birther/Bircher, which had to disappoint people looking for a moderate, pragmatic fellow as an alternative to President Obama. He might be a bit more sane than Sarah Palin or Michelle Bachmann, but not by much. He has shown himself an empty suit.
He blew whatever political goodwill he had. He was better as a mystery than as a reality. Donald Trump, who has never held any elective political office and has never held high military rank (as in Admiral or General), is completely unqualified to be President.
