That's because it really isn't an academic paper. He clearly stated that he was publishing it as a manifesto of what he would be researching going forward.

Would it be different if he just published it on a Medium or Substack blog?

I'm not an academic so I don't understand these weird feuds but seems pretty ridiculous to call someone out for lack of citations when they clearly disclosed the nature of that writing as somewhat unofficial and opinion-based. Maybe there's something I don't understand about those academic circles.