And I'm pretty sure I do understand what he's talking about. He's saying that the coming of AGI is entirely uncertain so we should act now. That's unreasonable in and of itself, and I don't need to go back and read all the history he's got with others to be able to tell that.
Opinion, anyway.
Edit: To reiterate why it's unreasonable- if we won't see AGI until it's already here, what, exactly, are we supposed to be preparing against? We won't know it even when we see it- so how will we know what to protect ourselves from?
Reasoning with uncertainty requires at least some amount of knowledge and the article goes to great lengths to point out there isn't any, in the case of AGI.
So there's no reasoning to be done, either. In that case, what are we talking about? "Beware of the unknown"? Well, OK. I don't know if the sky will fall on my head tomorrow so maybe I should stay home, just in case?