Why did you post it?
Because you know it's controversial and would create engagement.
If the nazi salute wasn't controversial (and rightfully considered hate crime) you would have ignored it.
BTW the first amendment does not condone hate speech.
Because even USA understands that there is a limit on everything.
You might think they are extreme in their views but rulings restricting speech are very, very rare.
And that has severe consequences as you see.
Popper said it many years ago.
Mainly as the defendant hadn't, despite the judge's specific encouragement, bothered to submit a proper defence or explore freedom of expression. So it could only be decided purely on the breach of the law. Then there were all the surrounding circumstances of how he set this up.
http://www.scotland-judiciary.org.uk/8/1962/PF-v-Mark-Meecha...
Thankfully in the US we have already codified free speech into law. Unfortunately there are still many who do not consider the liberties protected by the Bill of Rights to be a settled issue.