If he picked the nominee, thinking he needed 60 votes (or a promise to not filibuster or whatever you want to call it), then he was not willing to fight for a power that rightfully vests in the Office of the President.
That ain't "stong."
He resigned himself to respecting the power grab by the Gang of 7.
Would it have been smart for him to ignore the power grab by the Gang of 7? Maybe it didn't appear that way when he nominated Miers, but it better appear that way now.