I did glance through the entire thread before I posted.
It makes perfect sense to argue that what's achievable here matters: any alien that wants to travel to Earth has at some point to actually arrive here. At that point, they'd need to pay heed to our local laws of physics. Indeed, now that I think about it, if anything, that the laws of physics might vary would arguably count against the possibility of alien life visiting here (because they'd be obliged first and foremost to design spaceships compatible with their local laws, and why would they therefore bother trying to design stuff to cope with any other region of space?). I don't intend to waste much time on that argument because, as I say, I don't see a point in taking seriously the idea that the laws of physics *do* vary across the Universe.
Speaking of, I did see your post at whenever-it-was about the 2010 paper. I looked into it and, put briefly, it's an anomalous result that hardly undermines my point. It doesn't constitute hard evidence, there are question marks about the interpretation and legitimacy of those results, and certainly it's only *that* group that has made those claims, so there's no independent verification yet. That's not to say that it won't turn out to be true, of course, but signs are against it.
Still, it's a good thing to search for, and my understanding is that the assumption "the laws of physics are the same throughout the Universe" is constantly being tested. So far, as far as I'm aware, that assumption has survived such tests, and I'd be surprised if I'd missed such a huge milestone in our understanding of theoretical physics (I don't mean just an odd niche paper either: see, for example, the faster-than-light neutrinos paper(s) of 2011/12.)
I should have thought that the "Billions of light years away" figure was obviously not meant to be taken literally. I didn't see a need to specify our distance from every object in our galaxy and the Universe beyond, and I'm also aware that not everything is billions of light years away from us, but thanks all the same.
Granted that the chances of life emerging in the first place are a separate issue, but hardly unrelated. The logic would be roughly this: the smaller the chances of complex life emerging, then the greater the expected distance between us and our nearest alien neighbours, which in turn raises the difficulty of travel from them to us. Conversely, if intelligent life were more or less certain to emerge on any habitable planet, then obviously our nearest neighbours would be that much nearer. At present, I'd say that our understanding points far more towards the first case (ie, average distance between two planets holding intelligent life probably running into at least the thousands of light years) than the second, and while that picture may change, at the very least it has to be acknowledged as the picture *now*.