Who cares where McPain speak, He can speak at Pharook You if he wants to. The only people who want McPain to run are the media.
You're forgetting he's the democrat's Great White Hope. If by some insane confluence of events he won the Republican nomination the MSM would turn on him with such glee his head would do the Exorcist Spin. He has so much baggage that would receive a lovely airing.
Failing that, they are hoping to pump his ego for a third party spoiler bid.
McCain is about the only man who could get Hilary into the Oval Office in '08.