On the SOFA, Jonathan Schwarz seems to be of the opinion that "the deadline has no teeth, and the SOFA is already looking forward to U.S. troops staying there even after the 'withdrawal.'" If his interpretation is correct, or at least a plausible interpretation of the agreement, then McCain may not be as clueless as you and Mr. Ackerman say he is. Not about this, anyway.
The key point seems to be who on the Iraqi side needs to approve any extension or request for US troops to remain for training. Is is just Maliki, or does the Iraqi parliament get to weigh in, too? Schwarz could also be mistaken in his belief that Maliki wants US forces to stay in the country.