This instructor feels he’s stuck at the bottom rung of the ladder amd you’re coming from above where he wants to be and it’s making him feel inadequate.
Definitely talk to the Chief.
Matter of fact I’d ask to speak to both of them at the same time.
You have all the CRM experience and knowledge to deescalate the situation.
State your complaints and give him an opportunity to fix his attitude and gently remind them you like to be there but you don’t need to be there as formally you don’t even need the sign off.
All you need to do is rent the plane and bring it back.
Now....from personal experience, I’ve had one retired Airline Capt try and get his CFI reinstated.
After 15-17 hrs of training with me he pulled out.
He never got to Commercial standards from the left seat even and for the life of me he couldn’t fly single pilot.
So yeah they’re out there.
I don’t think you’re one of them though lol.