Fair enough, in a formal manner it’s empirical.
As a work, it’s political philosophy. Not science. Which makes it odd as a counterpoint to arguing the article in question is too aloof.
(Also, conflating irrational and illogical is unfounded. Nature is irrational. Per Caplan, individual agents may find it advantageous to act illogically. It doesn’t follow that one can’t use logic or rational thought to characterize the system.)