Because of your cousin's behavior, I would certainly bring it the landowners attention, if your close enough to the landowner. I don't tolerate that kind of behavior towards me from non family members, I sure as heck wouldn't from my own cousin...he deserves no respect from you and the farther away from him the better and if that means getting him kicked off a good hunting area, then so be it....I've read here people writing of "right"...neither of you have the "right" to hunt there, the landowner gives you permission....remember that and perhaps remind your pathetic cousin of that same information....if you are successful at terminating your cousins permission, be prepared for backlash...and good luck.