This is soooo not OK.
They should be arrested, tried and thrown in jail -- all of them, including the idiots who go along with these types of ideas and calls to action. Just look at that daemon fiend enjoying himself with smugness and delight.
1. It is calling for violence which can result in bodily harm and death.
2. To disrupt any gathering as they propose (fire alarms, sprinklers, stink bombs) is against the law. Panic can result in trauma & deaths.
3. To threaten burning peoples' homes is against the law and a threat of death. Most abodes go entirely up in flames in 3 minutes or less, the most deaths by fire are caused by smoke inhalation.
They act like it is fun to disrupt an historical gathering. To them it's like throwing toilet paper at the girl's house. Typical communist idiot, deplorable, sad operations. No wonder they fail. They were born to fail.