Alinsky also learned from Gramsci, as far as I can tell. At least they share the same strategy.
Where do you disagree with Horowitz?
The folks that protested in the 60's had gone to good schools and actually knew some stuff, so when their protesting days were over they could continue their push for their leftist agenda inside the system.
Most of the "organizers" of Occupy didn't do a good job at organizing. Even the left distanced themselves from them due to the rapes and generally foul conditions at the encampments.
And I don't believe they had the basic knowledge to continue the campaign forward. The Tea Party had much more success over that period than the Occupy movement did.
Also, Horowitz is one of those converted leftists with solid neocon leanings. He doesn't seem to have ever seen a war he didn't love and he carries his pugilistic attitude to debates on social policy which makes for good sound bites, but not much else.