> "it implies a second categorization which is false"

What is the second categorization implied by the quote from the author?

"I’ve invited a wide range of guest lecturers to address my classes, from Flat-Earthers to Christian apologists to global climate skeptics to Occupy Wall Street advocates. I’m proud of my work. I invited those speakers not because I agreed with their worldviews, but primarily because I didn’t."

Alternatively, read the sentence again https://brians.wsu.edu/2016/05/22/from-to/

How does this have anything to do with what ‘mizza said? I also took this as comparing flat earthers and occupy Wall Street. Grouping together a bunch of similar things and then adding in another dissimilar item as part of that group is a backhanded way of making connections between the items in readers minds.

It can work to create a positive or negative connection, but the connection is still implied

The connection is that they're highly controversial views from different groups. The professor is saying he was giving his students a chance to critically engage with various controversial ideas to sharpen their reasoning skills, and to get them used to dealing with views that might be quite contradictory to their own or to the mainstream.