Because there’s basically two possibilities here, both bad:
He had nothing to do with it, which means he has no control over what his own caucus is doing. That’s a failure of leadership, so he needs to go.
He was involved behind the scenes, but was too chickenshit to put his vote on record. Not only is that a betrayal of everyone who is about to get fucked by their medical premiums, it’s also abject cowardice, so he still needs to go.
Because there’s basically two possibilities here, both bad:
Of course, he reportedly was actually involved behind the scenes.