I think that the term “neoconservative” was being used here to mean a former leftist turned conservative, as opposed to adherence to the sort of ideology that we associate with neoconservatism today.
I think so, too. He was a former commie who made the journey to be on the Right, much like Whittaker Chambers and Malcolm Muggeridge did. What we know as neocons began in a somewhat similar place, but they ended up elsewhere, really not all that far from where they started as it turns out.