>>81391
Words have more than one meaning. Here's one definition I found for axiom:
>a formal statement or principle in mathematics, science, etc., from which other statements can be obtained
This fits. The action-axiom is the starting point of the Misesian system of economics. There is no principle behind it that is more basic.
You could also say it's self-evident. You still have people try to deny it, just as there are people who try to deny that a thing can exist and not exist at the same time, but that is literally just mixing words together and pretending they mean something.