It seems to me that privately held docks have their own right to restrict fishing just like leased docks. A privately held structure is property just like a farm pond on private property. It seems to me that the corp had to write something up granting leased docks the rights already afforded those who own as its a little bit of a gray area.

I could see the same situation if someone who leased a property that contained a farm pond attempted to enforce a no trespassing sign. It would be up to the actual owner to enforce the sign unless the owner passed that right on to someone who leased.