Rav Lior quoted Rav Kook as saying that the Erev Rav are Jews who support our enemies. This would definitely fit the NK and their fellow travelers.
As I’ve noted in the past, the NK are really small potatoes. They have not done anything impactful other than have others scoff at their nonsense. Eruv Rav, doubtful, misguided and foolish, absolutely.
However, when Avi Weiss writes articles in the NYT harmful to yiddishkeit in EY, he falls under the R Kooks description of Erev Rav. When other Rabbits of the OO movement hold press conferences and join in Court Cases which are designed specifically to harm Orthodox Jews, they meet the description of Eruv Rav.