'How come I wasn't murdered?'

Over on YouTube I was watching a special The Manson Women with both Patricia Krenwinkel and Leslie Van Houten. During the Tate murders Patricia said that she was told by Tex I think to go kill whoever was in the small cottage behind the main house, where William Garretson was staying right? As she headed towards it, she paused, realizing what was going on. So she decided not to enter the cottage.

This got me thinking of a line in the movie, when William is at the police station during the Polygraph test he says "How come I wasn't murdered?" while everyone else on the property was. So basically, is Willaim Garretson alive today because Patricia snapped out of it for a minute there? Or is this a little hard to believe?