For fucks sake Cata , regardless of how people personally feel about the tastefulness of the joke it is clearly a god damn joke.
Where is the joke though? In this one example the punchline is "Kill the immigrants". A threat wrapped around a joke. Sure it can be a joke, but it can be both. This is very hard to determine in written form. It is open to debate if someone said it, though.
Make it clear that its a joke and not a thread. Eg. "I said toast and juice, not toast the jews!", in this case its clear that its only a harmless pun combined with a historical reference. Even as Austrian I can laugh about that.
Make sure its not seen as threat.
Edited 9/5/2017 22:50:03