in the context of this guy being a large part of the “alt-right pipeline” (look, the name is bad, but he was a big part of feeding people that way), this looks like a way to say “look, the left may have some good arguments and seemingly reasonable proposals, but anyone can have those”
This is pretty common among conservative books (and other media more generally). It’s produced to give people who already agree with it confirmation that they are right (“It’s in this very authoritative book!”), not to convince anyone or convey new or interesting information.