I think even the Rationalists realize that science will solve all solvable problems, and time travel is not a solvable problem. That is why they would just simulate it all and consider it the same as the OG thing. "I made a non-interactive time travel machine that allows you to go back in time and look how WW2 went. You should see this! Saving Private Ryan starts playing."

I cut out the whole tech step and I'm simulating all the orgies I'm having in my mind right now!