Sounds like you are on their short list of people to fire and by documenting your demotion, etc. they are literally trying to protect from you suing them for wrongful termination.
If I were you I would just end the leave early, and next day is 1st day on the new job since you're already having a nice company A paid leave. Not sure but could be a fraud issue if you are taking Leave and actually working, just like a Disability leave and the guy is out there doing Ragnar or whatever, that's fraud and may have legal issues.
Not like you go from one to another without a small breather.