I’ve figured out why this guy can’t deal with your book (or your response): He has no understanding of fascism as a historical phenomenon, and relies excessively on contemporary efforts to redefine it. See, e.g., his silly discussion here. In the next section ,he attributes the first academic discussion of fascism to the Marxists,ignoring the prior (disavowed) Marxist analyses characterizing it as a close cousin of communism. Anyhow . . .
(Yes, I am procrastinating on other things I should be doing.)