Yes, is that (obvious) point being addressed in the paper? At first skimming, it just says that a "sufficiently souped up laptop" could, in principle, compute the future of the universe (i.e. Laplace's daemon), but I haven't seen anything about the subsequent questions of time scales.

Computing the future is cool, but computing the past state is also really cool as it essentially allows time travel into (a copy of) the past.