I think it's time to either start putting "realist" in quotes when he's described as such - or pointing out that it's a school of thought within international relations theories, not to be confused with what a layperson would consider 'being realistic' - much the same way "theory" when used in a scientific sense is misunderstood outside of that context.

That said, I'd agree he's gone off the rails - but I haven't dug into that school of thought to see if he's simply following it to what seems an absurd (but internally consistent) conclusion or not. I suspect that's what he's done, but it's not worth the intellectual effort to me to be able to say for sure (angels on the head of a pin, anyone?)