Suppose 3^^^3 copies of you are generated in the first second after you decide. Each one will have $5 less as a result of your decision. (for the sake of argument, lets say your responsibility ends there) Let's take a dollar as a utility unit, and say that by giving the matrix lord $5 you produce 5x3^^^3 disutility points across future worlds. But since everyone is producing copies at roughly the same rate (I think), any utility gained or lost is always multiplied by 3^^^3. This means that you can just cancel the 3^^^3 business out: for everyone you benefit, the positive utility points are also multiplied by 3^^^3, and so the result is the same.