Beat me to it, it occurred to me just a bit ago that this ought to have been the main objection in my first comment. Among the premises that there are a large number of natural intelligences in our area of the universe, natural intelligences are likely to create strong AI, and strong AI are likely to expand to monopolize the surrounding space at relativistic speeds, we can conclude from our observations that at least one is almost certainly false.
Beat me to it, it occurred to me just a bit ago that this ought to have been the main objection in my first comment. Among the premises that there are a large number of natural intelligences in our area of the universe, natural intelligences are likely to create strong AI, and strong AI are likely to expand to monopolize the surrounding space at relativistic speeds, we can conclude from our observations that at least one is almost certainly false.