I see that you didnt claim to present any facts, it just sounded as if you heard somewhere that cycling is a way to avoid long term damage. My mistake if I misinterpreted that.
As to your question. If someone gets far bigger than his natural ceiling would have allowed he will lose muscle mass when coming off drugs, regardless of damage done or not done to the HPTA
There is definitely a point where the muscle mass a very person is carrying is only possible because of the drugs he's on.
There is also good reason to believe that muscle mass built and maintained with the help of AAS will create a new 'set point' for what the person's body "sees" as normal. Meaning you are able to eat less to maintain a higher bodyweight than you may have been able to in the past. This goes for guys who do it without drugs though, so I dont think the AAS are to credit for that. AAS just get you to that higher bodyweight faster than otherwise possible