To be fair, that was not in the Court's opinion — it was in a concurrence by Justice Stewart. People like to quote it, but it wasn't actually the law.
(A concurring opinion is written by one or more justices who joined in the Court's (majority) opinion but wish to write separately to make some separate points or explain where they diverge from the majority opinion.)
And that standard was upheld by judges who were very clear that they were wearing blindfolds when it came to obscenity law. It is a huge step backwards - Rather, many many small ones by two irredeemable groups, both with good intentions and results that are comparable to serial killers - that we're even talking about "Hate Speech" as if it were a thing.
