He skips the vote when his vote would make utterly no difference.
The nomination passed 58 to 36. If Cruz had voted the nomination would have passed 58 to 37.
Since McConnell refuses to reverse Reid's unilateral abolition of the filibuster on judicial nominations the only way to block any of Obama's nominations is for all of the Republicans to vote against them. In this case, 12 RINOs refused to do so.
Well, to stop the nominations, all Mitch McConnell has to do is not schedule a vote. They don't need a filibuster - just no scheduling of votes. Really though, what's happening here is the Senate Republicans have slowed judicial confirmations to a crawl with the only real confirmations coming for District Court rather than Appeals Court judges. I would prefer that they held NO VOTES but I suppose that's not realistic.