I'm 24. Yes, he has a "right" to hunt wherever he chooses on that property based on the permission from the landowner. However, a decent person would respect your chosen area (I'd think) and find their own. How I've done this on a few shared properties is I swap numbers with the guys and we share spots and communicate via text where and when we'll be hunting. As long as everyone is good at communication we have no issues. I've also shared a property with a guy who had no respect for anybody and he was just a pain. He eventually got kicked off the property thankfully. Try talking to him, explaining what you want, hopefully he'll come around. If he doesn't, grin and bear it, not much else you can do.
-Jake