Money as defined by the regression theorem is an empirical phenomenon, not a praxeological one. It is based on several normative assumptions, for example: the non-existence of government, the non-existence of the digital, the non-existence of replicators and the stability and homogeneity of requirements for a medium of exchange. The first two conditions I mentioned are not fulfilled at the moment, the third one is, admittedly, science fiction but hypothetically thinkable, and the fourth one is just an unproven implicit assumption made after looking at historical developments.
Unless all four conditions are met, the existence of money cannot be deductively reasoned. And without deduction there is no praxeology.