Parent post isn’t arguing against the existence of laws. They’re illustrating that laws have limits and can be overcome by entities that wield enough power.
Look at the post above yours. Yes, some want to make the case that laws on the whole are essentially oppressive. Whether of not foucault made that case precisely, or whatever, is totally irrelevant if it’s what most people actual mean, viz that laws are the tools by which the powerless are oppressed.