Like almost all the other doomers, Eliezer never claimed to know which generation of AIs would undergo a sudden increase in capability resulting in our extinction or some other doom, not with any specificity beyond saying that it would probably happen some time in the next few decades unless the AI project is stopped.
Idk, a few years ago when chatgpt came out he was saying things like "if we're still alive in 3 years (...)" where chatgpt 3.5 was still a glorified transformer. And modern llms still are. It's the constant fear mongering that stings my nerves.
And well, I'm not surprised nobody knows which generation of Ai could undergo an increase causing our extinction, it's not even sure if there could exist such a thing, let alone know which generation