The qualification problem is related to McCain's military service. No former POW is qualified to serve as President. And the Presidency is different from being a legislator, or judge, or even a Governor: None of those offices have their finger on The Button. The POW experience — and I've served with and under, and commanded, former POWs; I'm no spring chicken — results in a certain inevitable impulsiveness and inability to make calm decisions under severe time pressure. I've seen too much trouble arise from this, including some fairly quietly handled issues that arose during Gulf War I.
If he chooses the Dog Washer as his VP candidate — a man who was himself too rich and good to serve — that will just make things worse. Besides, McCain is a squid, and worse yet a pilot... which says a great deal about his actual engagement with military leadership, but that's an argument for another time.
So even if I agreed with his ideology, I couldn't vote for McCain.