I guess it depends what you mean by a "doomer." If, to you, "doomer" means you have to act like Yudkowsky and go around saying it's urgent to unilaterally destroy all GPU data centers with military force then no he's not a doomer.
But if "doomer" is allowed to include a Cambridge educated professor and Fellow of the Royal Society with a 'stiff upper lip' who finds himself surprised to realize that the caterpillar of humanity is creating the butterfly of AI and that "the caterpillar gets converted into a soup out of which the butterfly is created" as quoted in the first tweet thread that you listed, then maybe he could deserve the doomer label.
In another interview, in his response to 'why we should be scared' asked by a reporter he said that "as a friend of mine said, it’s as if some genetic engineers said, we’re going to improve grizzly bears; we’ve already improved them with an IQ of 65, and they can talk English now, and they’re very useful for all sorts of things, but we think we can improve the IQ to 210." Presumably this guy is understated enough to trust the listener to understand that he thinks that might reasonably scare someone.
Of course he's a doomer. He's compared himself to Robert Oppenheimer and by his own admission the only reason he isn't calling for a complete halt to all AI research is because he's too pessimistic it'd be possible. He describes a man who wants to literally bomb datacenters as "not crazy", just "not helpful" i.e. he'd be totally on board with such tactics if he thought they were more plausible.
> Talking about the dangers of AI is not the same as being a doomer
It is in fact the same thing as being a doomer if you're claiming that something unstoppable will lead to doom, in the same way that pointing out government coverups of lab leaks technically makes you a conspiracy theorist.
But if "doomer" is allowed to include a Cambridge educated professor and Fellow of the Royal Society with a 'stiff upper lip' who finds himself surprised to realize that the caterpillar of humanity is creating the butterfly of AI and that "the caterpillar gets converted into a soup out of which the butterfly is created" as quoted in the first tweet thread that you listed, then maybe he could deserve the doomer label.
In another interview, in his response to 'why we should be scared' asked by a reporter he said that "as a friend of mine said, it’s as if some genetic engineers said, we’re going to improve grizzly bears; we’ve already improved them with an IQ of 65, and they can talk English now, and they’re very useful for all sorts of things, but we think we can improve the IQ to 210." Presumably this guy is understated enough to trust the listener to understand that he thinks that might reasonably scare someone.