Because if something exists, at least so far in our experiences, there has always been a way to get to it. At least that I can think of, I cant think of anything that exists that we couldnt get to. If something is travelling away from us at the speed of light, then we cant catch up to it with our current technology, which is what I said (given that people once said we couldnt go to the moon but that was down to tech limitations at the time), but eventually we could get the technology to catch up with it (by some sort of warp drive or folding space or some other method of taking a short cut so that we arrive ahead of it and intercept it etc).
I mean I'm just a normal gamer guy, I'm no scientist or quantum expert, it just seemed to me an odd thing for him to say that something exists but we will never , ever , even in hundreds of millenia time , be able to get to it. To me , it seemed to either be a contradiction or a dismissal of what we may achieve in the distant future ( in both terms of technology and understanding)