Maybe it's not about wealth inequality so much as power inequality. In a true democracy, the little guy is empowered, which is I think where the author of this article is seeing the Alinsky/Sanders intersection.
We live in a kabuki democracy, where we get to vote but power operates behind the electoral outcome, largely immune to the will of the electorate.
Looking at Sanders' life work, I think he consistently has tried to address this problem. A noble work, hopefully people wake up and lend a hand. I
t's going to take a lot of people deciding that supporting one political party's establishment candidate over the other's isn't going to get it done, and that establishment politics is entirely unable and unwilling to address the major issues we must deal with. The power behind the politicians won't deal with the issues on their own, either, they are mostly in it for a buck.
Leaders are invaluable in these efforts, and Sanders is a gift. Hopefully more will emerge, and soon.
From the article the OP is about,
We must believe that it is the darkness before the dawn of a beautiful new world; we will see it when we believe it. - Alinksy