Maher makes a good point about hindsight

And judging people by their past mistakes. We need to see them as they are now, as they've grown and changed their opinions. The problem with his using Biden as an example is that Biden really hasn't changed that much on the policies that the majority of we the people now hold. And his point that we would have been like that back then too doesn't hold for Sanders, as Sanders was like he is now back then too.