Given that the inhabitants of these hypothetical simulations don’t know the (external) time, your argument seems to require a principle along the following lines: “If at each precise time t, X is more likely true than Y, then overall X is more likely true than Y”—even when X and Y are funky conditional indexical anthropic things like “if I am alive then I am in a simulation”. But no such principle is true.
Given that the inhabitants of these hypothetical simulations don’t know the (external) time, your argument seems to require a principle along the following lines: “If at each precise time t, X is more likely true than Y, then overall X is more likely true than Y”—even when X and Y are funky conditional indexical anthropic things like “if I am alive then I am in a simulation”. But no such principle is true.
(In other words, I agree with ike.)