The anthropic principle selects certain universes out of all possible ones. In this case, we can only exist in the subset of them which admits humans but prohibits strong AI. You have to first subscribe to a version of many worlds to apply it, not sure if you do. Whether the idea of anthropic selection is a useful one still remains to be seen.
My point is more that expansion of the strong AI would not occur at the speed of light, so there should be very distant but observable galactic-level civilizations of AIs changing the very nature of the regions they reside in, in ways that would be spectrally observable. Or, in those multiverses where a local AI respects some sort of prime directive, we may be left alone our immediate stellar neighborhood should nevertheless contain signs of extraterrestrial resource usage. So where are they?
If Strong AI turns out to not be possible, what are our best expectations today as to why?
I'm thinking of trying myself at writing a sci-fi story, do you think exploring this idea has positive utility? I'm not sure myself: it looks like the idea that intelligence explosion is a possibility could use more public exposure, as it is.
I wanted to include a popular meme image macro here, but decided against it. I can't help it: every time I think "what if", I think of this guy.