I reported a threatening message from a guest after I left an honest review (he was lucky to even get two stars) and Airbnb has yet to respond from the initial "tell me what happened" email four days ago. I have emailed once a day trying to followup because I feel my property is now vulnerable since this guest was a local and I am an absentee property owner. Airbnb claims to have zero tolerance for such behavior yet has not demonstrated that to me even with as much as a reply to my concern. I have had 100+ stays with only a couple really bad ones; this guy was in the top two worst ever. I am removing my listing from Airbnb and going with another service, such as VRBO. It sure doesn't seem that Airbnb is pro-host these days.
They usually respond quickly if you post your experience on social media. Hosts shouldn’t have to do this, but they do.
PS: The is a hosts only blacklist group on Facebook where you can post warnings about destructive or dangerous guests. Airbnb is not very proactive about removing them from the platform.