Should he be faulted for that? Allowing Trump to win would be disastrous for the party. I'm not sure why they haven't recognized this.
Since letting Hillary win would be disastrous for the country, he absolutely should be faulted for such short sighted thinking. It's another example of the same stupidity that caused many to stay home in 2008 and again in 2012. That worked out so well for us let's try it again in 2016!