Sets are 0-categories, so this critique would also suggest that 0-category theories, set theories, are circular too. But we actually place formal logic before s

Sets are 0-categories, so this critique would also suggest that 0-category theories, set theories, are circular too. But we actually place formal logic before sets, and then use sets to reflectively study formal logic without infinite regress. This is a version of the general pattern that there are no informal justifications for formal reasoning. Once a person tastes formality, then they can judge for themselves whether to adopt it, but there's no self-sustaining proof statement.