Suppose we pick out one of the histories marked with a 1 and look at it. It seems to contain a description of people who remember experiencing time travel.

Now, were their experiences real? Did we make them real by marking them with a 1 - by applying the logical filter using a causal computer?

I'd suggest that if this is a meaningful question at all, it's a question about morality. There's no doubt about the outcome of any empirical test we could perform in this situation. The only reason we care about the answer to such questions is to decide whether it's morally right to run this sort of simulation, and what moral obligations we would have to the simulated people.

Looked at this way, I think the answer to the original question is to write out your moral code, look at the part where it talks about something like "the well-being of conscious entities," taboo "conscious entities," and then rewrite that section of your moral code in clearer language. If you do this properly you will get something that tells you whether the simulated people are morally significant.