He is coming from common sense and maybe where he lives he has a very good feel of what people are thinking.
For example I live in South Florida and work in wealth management. Not for billionaires....but people who are living the American Dream, have saved their whole life and can retire eventually or are going into retirement. I would say my clients range from incomes of $125,000 - $550,000 annually as well as clients who have built successful business and sold them to retire comfortably.
Simply put mostly generation Y, X and baby boomers. Meet your most interested and active voters in the country.
All of them.....every single one will never vote for Sanders over Trump. Fact. That gives me a very strong indication that he will not have a real chance to defeat him.
Call it a simplistic look at the election....call it foolish....call it whatever you want. But I have a ton of common sense and instincts. I am as successful as I am because of my ability to read people, know what they feel, and want and how to help them get there financially. I also am a great listener. My client base are the mass affluent (500K-10MM to invest) and some ultra high net worth family office clients (Clients with 25MM or more to invest).
They give me a great sense of what successful Americans want. They do not want Sanders. In fact anyone but Sanders or Warren.
And BTW these same people....most voted for Obama in the first election. Most voted for Bill Clinton twice when they were in their 20's and 30's and 40's.
It ain't happening if Sanders is the nominee. No way IMO.