He had Harden as his MVP until the last 3 weeks of the season IIRC. He had Harden 2-3 a few weeks ago.
I don't it matters all that much. These guys are skilled at starting with a position and then looking for arguments to support it, rather than the other way around. Since all year the argument was Westbrook vs Harden, he had to prop up one to bash the other. If Westbrook was out of the picture, he'd probably have been pushing for LeBron or Kawai as MVP.