Either they would have arrived already (and taken over the galaxy, suppressing us in the process) - or they have yet to arrive. The chances of them initially showing up around about now are going to be pretty small.
They apparently haven't arrived here already - unless they seeded us originally - else where are they? So, if they are out there, they have yet to arrive.
I don't really see how all this makes much difference to the original argument.
The point of that argument was that seeing yourself alone in the galaxy with no aliens around is only to be expected - if the first intelligences rapidly expand and suppress the subsequent development of other intelligent life. So, being first is not so much of a miracle.
Why do we imagine our actions could have consequences for more than a few million years into the future?
Unless what we believe about evolution is wrong, or UFAI is unlikely, or we are very very lucky, we should assume there are already a large number of unfriendly AIs in the universe, and probably in our galaxy; and that they will assimilate us within a few million years.
Therefore, justifications for harming people on Earth today in the name of protecting the entire universe over all time from UFAI in the future, like this one, should not be done. Our default assumption should be that the offspring of Earth will at best have a short happy life.
ADDED: If you observe, as many have, that Earth has not yet been assimilated, you can draw one of these conclusions:
Surely, for a Bayesian, the more reasonable conclusion is number 2! Conclusion 1 has priors we can estimate numerically. Conclusion 2 has priors we know very little about.
To say, "I am so confident in my beliefs about what a superintelligent AI will do, that I consider it more likely that I live on an astronomically lucky planet, than that those beliefs are wrong", is something I might come up with if asked to draw a caricature of irrationality.