the term came into existence explicitly to dilute the free software movement and make space for evil companies to do evil things.

It did. That has nothing to do with whether Open Source Software refers to software that uses an OSI approved license. It's the people trying to cloud a technical term with a dictionary meaning in order to be parasitic on FOSS without being FOSS who are being divisive, not people using the terms normally. Stallman isn't doing that.

if you were to buy this then it may continue from that logic that everything covered in the article is well labelled open source.

I mean, this is just nonsense. Stallman says Open Source is bad, therefore everything bad is Open Source?