So while he does not "own" this land, he has to maintain it. It is a total dick move to make the home owner's life more difficult by killing the grass with your dogs piss. Typical dog owner sense of entitlement (worse than the homeowner's in this case), why is the world your dogs toilet? Train it to do its business in your own yard...
A dog taking a leak doesn't instantly kill grass. My dog's pisses along a 10' section of fence multiple times a day. There is ~6" of grass that is hurting along this fence. When he used to be able to go anywhere in the back yard, there were no marks.