If we work from assumptions that make it likely for the universe to contain a "large number" of natural intelligences that go on to build UFAIs that assimilate on an interstellar or intergalactic level, then Earth would almost certainly have already been assimilated millions, even billions of years ago, and we accordingly would not be around to theorize.
After all, one needs only one species to make a single intergalacitc assimilating UFAI emerge somewhere in the Virgo Supercluster more than 110 million years ago to have assimilated the whole supercluster by now, using no physics we don't already know.
Which is evidence against the possibility of AI going FOOM. I wrote this before:
The Fermi paradox does allow for and provide the only conclusions and data we can analyze that amount to empirical criticism of concepts like that of a Paperclip maximizer and general risks from superhuman AI's with non-human values without working directly on AGI to test those hypothesis ourselves. If you accept the premise that life is not unique and special then one other technological civilisation in the observable universe should be sufficient to leave potentially observab...
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.