A Relative Question

I have already proposed in an earlier post my thoughts on Light being "Dark Matter."  I just think our scientists have their numbers wrong and it is a possible solution.  The following is a question I would love to have answered, however, regardless.

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An imaginary star system, ISS, is 500 light years away from us.

On a certain day, X, two identical robots are built, Robot A and Robot B, robots capable of existing millions and millions of eons.

Less than a minute after creation, Robot A travels just under the speed of light to earth.  Now, the light from the imaginary star system, ISS, will reach earth 500 years after the moment Robot A begins his journey.  Robot A arrives 500 years and one day after his departure, and is therefore 500 years and one day old.

How old is Robot B when Robot A arrives on earth?

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There was a time I think I could have answered this relativity question.  I do not believe it is terribly difficult if you know the right equations.  Yet, this is not my real question.

I know Robot A will be travelling into the distant future as it speeds towards earth, as compared to Robot B back in ISS, and therefore, Robot B will be much older than Robot A.

My real question:  why do we believe the light travelling to earth from ISS, at a speed slightly faster than Robot A is not time travelling?

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Why is this important?  I do not believe this relativity is taken into account with regards to our Universal calculations.  It is my impression that scientists currently just compute with regards to the light source (here ISS) having aged the same 500 years as the light which we see.

Consider.  If Robot B (and again, I have no idea with regards to the ballpark figure so I'll go high and low with examples) is 20,000 years old when Robot A reaches earth, ISS, too, has aged 20,000 years.  How much has the system changed or moved as compared to a computation which relies on ISS having only aged 500 years?  What if Robot B has ages 2,000,000,000 years?

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Now consider a second system, SS2, half way between ISS and earth (though just askew by our view) which Robot A passes 250 years and 12 hours into his journey.  When Robot A reaches earth, the light from this second system has travelled 250 years, but has not the system aged nearly half of that which Robot B has aged?

If ISS is 2 million years removed from where we think it is, and SS2 is 1 million years different, how off can any calculations attempting to judge their mass or velocity be compared to calculations thinking only 250 and 500 years have passed?

This would mean that none of the stars we view are anywhere near where we think they are relative to each other.  Wouldn't this drastically alter current calculations?

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Now, someone once tried to tell me light doesn't time travel.  I didn't understand his answer.  I still don't get how it is possible.  Wouldn't it mean ISS only ages drastically if something other than light travels away from it? 

But moreover, how the hell can we know if light does not time travel?

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If someone with the knowledge happens to read this, do let me know why I am wrong.  It just doesn't make sense to me that Robot A and the extra day it takes him to travel to earth would make a difference.

And if I happened to ask a question that changes the way you physics folk compute the Universe, hurry up with my Nobel so I have something to leave my kid.