Bernie Sanders is a socialist,[1] and social democracy is a type of socialism.[2] That blog you linked to is, at best, advocating a very idiosyncratic use of terminology.

1: http://www.washingtonpost.com/wp-dyn/content/article/2006/11... 2: http://www.britannica.com/topic/social-democracy

That doesn't matter to most of America. They hear "socialist", "social something", and they are going to be against it.