Yes crab, it is more or less what I'm saying. My idea about horizontal stabilizer stall is coming from the SA 365C model. On this helicopter when correcting a nose up upset, an overeactive pitch down autopilot control action (without pilot's correction) could possibly stall the horizontal stabilizer. The resulting sharp nose down attitude was said to be critically recoverable below 500' AGL.
Although I've never heard something alike on 365N series, I was thinking that perhaps this could happen with only 50% stabilizer surface remaining.... just a guess ... helicopter aerodynamics are more esotheric than something else.
BTW I know an other type of helicopter (Lama SA315) that crashed after too much pitching nose down without the horizontal stabilizer installed. The pilot was very experienced but never could recover from a loooong dive (more than 500') in mountain flight.