I'm assuming that expected value of running the computer is dominated by universe-optimizing AGIs it generates, which would have much better conditions for bootstrapping from a well-defined program in a fully-functional computer than if they have to do it boltzmann brain-style.
Our world already contains many computers that are subject to quantum fluctuations. Some of them even use quantum noise random number generators, so you just need a small glitch to accidentally execute that data, thus creating all the universe-optimizing AGIs you can imagine.
From David Deutsch's The Beginning of Infinity:
I'm not so sure we have the computing power to "simulate a person," but suppose we did. (Perhaps we will soon.) How would you respond to this worry?