>My read is that they are casting a larger net than the traditional definition

I doubt the book is about punching near centenarians who were members of a specific political party in the 1930s and 1940s. "Nazi" is now colloquially used as a general term to describe fascists and bigots.

Here is the Merriam-Webster definition for the word[1]. The traditional definition is definition 1. The definition the book is using is definition 2.

You don't need to wear a swastika to be fairly categorized as a Nazi according to that second definition. Some people espouse Nazi and Nazi-like ideals without self-identifying as Nazis. That seems to be the underlying meaning of the above passage.

[1] - https://www.merriam-webster.com/dictionary/Nazi

You edited "hateful groups are spewing vile..." out of the beginning of that quote which is important because even if people "exaggerate just how "anti" such stances are", there is still a difference between an anti stance and a hateful and vile stance. It isn't talking about opposing affirmative action, being against more immigration, or disagreeing with gay marriage. If you hear words like "Nazi", "White Nationalist" "hateful", and "vile" only to immediately think "they are talking about me" that is a problem on your end.