What sort of proof of ownership did you provide?
DJI has never nor will they ever Unbind a Drone from a users account. it's their Policy. ( Per DJI: DJI will only unbind a drone if that action is initiated by the original account holder).
So how...
Education is key!
I have only been approached twice by LEO in my 10 years as a drone pilot and wound up helping one of them purchase a drone and then trainned them how to use it.