I am familiar with Don C. Around Leeds, he appears to be well known as a writer of letters to the editor of the local newspaper.
The bone he picks, I suppose, is that I chose to quote Spencer's letters from Johnson's book and to cite them with reference to that book. That reference is far more accessible than the originals. To Don C, this becomes "second person" testimony.
The originals of C. C. Spencer's letters to Guy Johnson, and of many the other letters quoted in my article, are in special collections at the library of the University of North Carolina. I have examined them. I vouch for their contents as published by Johnson.