If the boat is "parked" wrong I see it perfectly reasonable to move it. Of course with care and fix the mooring ropes properly so you don't upset the owner.
After all it's not your fault that he didn't appreciate the space well enough and didn't consider that other boats have to come there also.
Never sailed a boat and don't know how hard it is to put it on the right spot so I'm just assuming. I will learn though in July to sail a 6 meters with one motor boat.
At least on the open waters :)