Since when has a company enforcing their TOS been discussion worthy? Their content policy clearly outlines what is considered "Unwelcome Content" and it seems like the majority of the alt-right thread would be classified as "Violent Content" under Reddit's terms.
I think a much more amusing enforcement of such policy would be for Twitter to ban Donald Trump, thereby also banning the @POTUS account for the term of his Presidency for "Abusive Behaviour" on Twitter such as openly harassing the cast of Hamilton.