@Aniketh-Dhanraj0 Any person can sue any other person or threaten them with a suit. Can they get away with it? Only if you let them.
Copy or take pictures of the off-portal messages and paste them into the message thread on AirBnB that is pertinent to the booking. If AirBnB can validate the threat, the errant host may be sanctioned.
By the way, this method also applies to hosts who have had guests threaten them. If the threatening communication is on the platform where AirBnB can see it, sanctions may occur.
(But don't count on any assistance from outsourced customer service).