The main argument here is "if you can go as fast as traffic then you are more like traffic". Not Just Bikes did a 1.5 hour treatment on how US/Canadian bike infrastructure got the way it did, and the one man responsible: https://www.youtube.com/watch?v=pRPduRHBhHI
TL;DW
This guy believed that only "real cyclists" should be riding, i.e. people who ride racing bikes as fast as they can. Casual riders need not apply. He wrote a book on how to design streets for bikes based entirely around "real cyclists". It's commonly used today. The infrastructure it recommends is dangerous for most actual people who bike, so no one bikes. The video is a great 1.5 hr rant though, very entertaining.
Point is, this article falls into the trap of accepting the whole "real cyclist" framing of the argument. If there's separate bike infrastructure, then the idea of needing speed to integrate with car traffic goes away, and the whole article is moot.