Yes, I'm late. So what. People miss the fundamental point.

The characters clearly state that since their level of emulation is approaching infinity, anything they do to their child universes will simply be reflections of the parent simulations.

Look at it this way. You rewind to 1942. You're going to kill Hitler. But your universe simulation is so in tune to the parent universe they're already doing the same thing. What you interprets as free will is the averaged responses of all parent universes. At some point in the simulation universe 2 billion plus above you someone actually has an original though to kill Hitler. This is simply re-emulated endless times.

There are no original thoughts in this view of the universe.