It’s pretty simple.
First claim: Hierarchies are social constructs! It’s all made up so that some people can hold power over others!
Peterson’s response: No, hierarchies exist in nature, going way, way back - you can find them even in crustaceans, which split from us some 300 million years ago. They even have the same neurological apparatus for it as we do. It’s not socially constructed.
That’s it. He isn’t saying we should emulate lobsters. He isn’t even saying hierarchies are an unalloyed good. But he is saying that they are not something we came up with. They serve a deep function and you are not going to get rid of them by just switching to a different economic system, per the socialist illusion.