The meme is based off not having an inner monologue, making the person far more susceptible to, "The loudest voice"(Because they don't question anything) which in our modern day is the media. The media is currently strong left leaning, which means those NPCs(people without monologue) tend to be swayed by the mass media. It's incorrect to say, "Right wingers are the real NPCs" as they do not have control of the mass media. They were the ones who, despite all the propaganda bombarding them everyday constantly, still were able to question the narrative and arrive at a separate conclusion from the masses.
That being said, it is still possible for right wingers to be NPCs(And most of them are to an extent) within their own communities. It's a matter of how much you let yourself be an NPC (This could correlate to the fact that people use inner monologue to varying degrees in the study) When you look at the average r/The_Donald user you'll notice their NPC behavior starts where their tolerance for beliefs ends. Some people believe everything with no question like leftists, some people question a little bit of the narrative and become centrists. Others will question most of the media narrative like Trump CivNat supporters, but they will use the same NPC behavior they complain about, the second you ask them to apply their "Critical thinking/ Questioning" to the Jewish Question.
I think these varying ideologies may coincide with the rates of inner monologue. For example something like this ~, 0% Hard Left, 50% Centrist, 75% CivNat, 100% NatSoc.