If this portrayal of "environmentalists" as sociopathic monsters had been created by right-wingers, I'd get the joke. I'd think it was a pretty tasteless joke, but at least I'd get it:
But no! It's leading "environmentalists" themselves who, it seems, find it amusing to imagine killing, in their blood, anybody who doubts or dissents from their agenda.
The spirit of Lenin, and Stalin, and Mao, is alive and well, and hanging out amongst these deeply scary people.