This comment perfectly encompasses
why it's a slippery slope. The definition of "literal Nazi" is use so broadly in political discourse. Politicians have been called Hitler and Nazi since Hitler and Nazis became a thing.
The massive danger is going to be the countless false positives this thinking generates. Just like the craziness of arresting the guy whose dog made a nazi salute in the video.
He would be denied access to social media because of stupid interpretations of a joke.
This isn't about defending or persecuting Nazis, it's about protecting the public from systems of abuse.
Not to mention the ineffectiveness of online censorship. The only worse thing are Nazis organizing on public platforms is forcing them to congregate only with other Nazis on radical websites where no one will challenge their worldview. But that's a totally different discussion.