The Soviet Union was also a Socialist country and that was a socialist policy.
Also, problem with what you are proposing. There are a few schools of Socialism. De Leonist and a few other obscure ideologies aside the biggest two schools of socialist thought are Marxist-leninist and Prussian. The prussian socialist school is basically the economic half of National Socialism, Strasserism, and Nazbols.
I really don't think you want to subscribe bernie to the prussian school. And I have heard nor seen any indication from him he is subscribed to one of these obscure schools. So I think your kinda limited to admiting that his socialism is of the marxist-leninist school.
Also 20% ownership... firstly that seems like a stepping stone goal not an end goal. Secondly if it is an end goal, I have not seen him go after coopt buisnesses or communal groups. In addition how is he going to enforce it? Make sure that control never rises above 20% and really have the balls to crack down on more extremeist marxists who try to seize more of the means of production of a company that already has met their 20% goal.
Look man I got my degree in this shit, and it is my personal hobby. You aren't going to win an argument about political philosophy regarding Bernie Sanders' outspoken and clearcut Progressive Democratic Socialism.