You might try to shame him into behaving less childishly. I'll go find someone else to play with. Property rights provide the means for implementing the right to one's life. If someone is able to dictate to you how you will dispose of or use your property, then you are, to that extent, his slave. You must be free to use your property in any manner you want so long as you do not endanger the life or property of someone else.
Property rights help delineate the proper boundary between one person and another.
They help us recognize those aspects of the world which are subject to our control and which are under the authority of others. Property rights help ensure peaceful interactions among individuals. Without them, only chaos and ceaseless conflict can result.