I think he sees all things through the prism of race. He picked the dumbest white man he could find. It was not a coincidence.
Presidential candidates all tend to pick those they deem inferiors, just so the potential veeps don’t steal the limelight.
In Obama’s case, it was almost impossible to find an inferior, but he somehow managed it.
Biden, of course, missed his true calling; he should have donned the grease paint and driven one of those mini-cars around in a circle for Ringling Brothers.
I think you have hit the nail on the head...and Obama chose accurately, so far as I can tell.