I'm not planning to tile the universe with myself, I just want myself or something closely isomorphic to me to continue to exist. The two most obvious ways to ensure my own continued existence are avoidance of things that would destroy me, particularly intelligent agents which could devote significant resources to destroying me personally, and making redundant copies. My own ability to copy myself is limited, and an imperfect copy might compete with me for the same scarce resources, so option two is curtailed by option one. Actual destruction of enemies is just an extension of avoidance; that which no longer exists within my light-cone can no longer pose a threat.

Your characterization of my utility function as arbitrary is, itself, arbitrary. Deal with it.