Reich, after all, was appointed Secretary of Labor by Bill Clinton. Prior to that, Reich was a professor at Harvard - but when was the last time you saw a professor's choice for President noted in places like Politico and The Hill? Reich's relevance to this or any election derives from a position which Bill Clinton bestowed upon him.
Which is not to say that Reich owes Bill, or Hillary, unquestioning loyalty. Were Hillary to suddenly start espousing ideas similar to Trump's, Cruz's, or Rubio's, I would not blame Reich in the slightest for putting aside his debt of gratitude to Bill Clinton, and supporting Bernie.
But as Bernie and Hillary and Reich himself readily admit, there's nothing like such a significant level of difference between the two Democratic candidates. And that being the case, I think Robert Reich owes it to Bill Clinton to, if not outrightly endorsing Hillary, at least not endorsing Bernie this primary season.
Because, although I don't think loyalty should count for everything, it should still count for something in this world. The First Lady of the President who appointed him Secretary of Labor, and therein the position which now makes his opinion count for anything, deserves better now from Robert Reich in her own run for the highest office in the land.