Zed Shaw, whilst his approach to certain issues may be questionable, is not "a writer rather than an engineer".
Zed is known as one of the most prolific and capable software engineers around and I have heard his C code for Mongrel 2 server https://github.com/zedshaw/mongrel2 described as being amongst some of the best examples of C code to study, learn and understand (trying to find the link that said that). I hold his work in high regard.
I don't agree with everything that Zed does and think it's a pity that his combative and dogmatic nature detracts from the core message about his work, but the author of this blog post is off track if he is trying to suggest that Zed doesn't know what he is doing and is "a writer" rather than "a software engineer". Zed is a (cantankerous) software engineer and a writer.
The attempt to discredit Zed's credentials just discredits the blog post and its author. When criticizing, criticize the work rather than the person.