As somebody else explained, if he had showed up to vote against it the amendment almost certainly would have still failed by 1 vote. The party whips would have

As somebody else explained, if he had showed up to vote against it the amendment almost certainly would have still failed by 1 vote. The party whips would have just required one of the other "no"s to switch. The reality is that party leadership controls exactly what gets voted on and when, and to a large extent predetermines who is allowed to vote yes and no. The rest is just theater.