R-44 Flight Instructor reported while attempting an auto-rotation landing another aircraft entered the runway resulting in the Flight Instructor taking evasive action to avoid a collision with the other aircraft.

Narrative

On an instruction flight with a private pilot student; set up to do a 180 autorotation from the right downwind of ZZZ runway XX. Made a right downwind call on the CTAF; including that we were to conduct a 'power off 180 from 1700 to runway XX'. I emphasized our intention as Aircraft X was in the run up pad to runway XX and was not sure what his intentions were. Additionally made a short base to final call. After leveling out from the 180 turn on final; noticed Aircraft X had taxied onto runway XX and was beginning his takeoff roll. Simultaneously; both myself and the pilot of another aircraft got onto the CTAF; him making a takeoff call; me rapidly saying I was 'on short final runway XX airplane on the runway hold position'. After these calls were made; I immediately took controls and side stepped to clear runway XX to the East; nearly overflying him; he made a call at this point saying 'whoever that [expletive] in the helicopter is needs to get the hell out of my way!' I advised him at this point that I was on short power off final when he taxied out and that we would hold East of the runway so he could depart. He made no further calls after this point.