A couple of follow-ups here: Andrew Gelman has, I think, the best commentary on Guzey's critique.

https://statmodeling.stat.columbia.edu/2019/11/18/is-matthew...

https://statmodeling.stat.columbia.edu/2019/11/24/why-we-sle...

To my knowledge, Walker hasn't responded to Guzey's criticisms. The other issue that has emerged in the weeks since Guzey published his critique is that Walker seems to be using the erroneous claims in his book in his papers. Relevant exchange here: https://statmodeling.stat.columbia.edu/2019/11/24/why-we-sle...