Your comment would seem much more applicable to Mitt Romney than to McCain. While some here doubt that Mitt is moving very far to the right, I haven't seen any evidence that he's been moving actively to the left over the last few years the way McCain has. McCain may have been a conservative once (more likely, IMHO, he happened to take conservative positions without an understanding of why they were correct) but he certainly isn't anymore. Even if he hasn't yet become as much of a leftist as Hillary or Obama, he's getting there.
I for one have noted Romney’s rightward motion and will be far more inclined to support him next election if he stays firm to his newer convictions. I also think he did the right thing withdrawing AND endorsing McCain.