Having made this argument myself I’d like to point out that the author made a tactical error. Rather than saying Fascism is LEFT, simply say that it is a form of Marxism. Otherwise the argument devolves into what is “right” and “left”. It also helps with the argument “but Nazi’s killed Socialists”. The answer to that is Marxists of different stripes have a long history of killing each other to determine who will be the ones in power.
“simply say that it is a form of Marxism”
Actually, Hitler specifically rejected Marx’s brand of socialism. He was socialist, but very anti-Marxist.