You'll encounter this kind of intrusion every so often! That's why I try to find spots that nobody else even thinks of going into. It might be that you had selected the best spot and he didn't want to miss out. It's rude, but on public land there's not much you can do. Maybe report him if he does something illegal, or talk to him if you see him. I'm not quite sure of the potty break you're talking about, but I personally don't think urinating affects deer hunting! I occasionally pee outta' my stand!!!