It's interesting to tie some thoughts in his writing to EA, but based on just the evidence here, I'd object to calling him an EA.
If to these tremendous and awful powers is added the pitiless sub-human wickedness which we now see embodied in one of the most powerful reigning governments, who shall say that the world itself will not be wrecked, or indeed that it ought not to be wrecked? There are nightmares of the future from which a fortunate collision with some wandering star, reducing the earth to incandescent gas, might be a merciful deliverance.
It's fun to call a famous figure an EA, but to me, identifying a risk in your writing = futurist, taking actions in pursuit of doing the most good you can = EA. I think to some doing things like calling famous figures EAs could be seen as the movement being spurious and status seeking, so I have a particular sensitivity to it that makes me want to flag this here.
The impression I got from a recent biography of Churchill was that he was very concerned, and made constant reference to, the risk of something like value lock-in should the Axis powers win WW2 - i.e. that it stood a chance of being a near-irreversible dampening of future human potential, not just a terrible catastrophe for the people alive at the time. Perhaps that attitude is connected to these other statements of his.
Nitpick: When you say "already they were most excited, not about fusion, but fission", I think that must be the wrong way around. The short quotation that follows describes (or at least gestures at) two ways of extracting energy from nuclear reactions. The first (hydrogen to helium) is definitely fusion. The second (combining hydrogen's electrons with its nuclei) ... doesn't sound like it would actually work, but at any rate there's no possible way that it could be called fission.
The second definitely doesn't work because it's actually an endothermic reaction (reverse neutron decay), but Churchill couldn't have known that in 1931 before neutron mass was measured accurately.
From the phrasing its possible Churchill was thinking of matter anti-matter annihilation (which I think was fairly new theory at the time) but he was mistakenly identifying the proton as the anti-particle of the electron (instead of the positron).
Churchill as a futurologist needs to be compared and contrasted with H.G. Wells, the foremost futurologist of their day.
My takeaway from this:
Churchill—when he wasn’t busy leading the fight against the Nazis—had many hobbies. He wrote more than a dozen volumes of history, painted over 500 pictures, and completed one novel (“to relax”). He tried his hand at landscaping and bricklaying, and was “a championship caliber polo player.” But did you know he was also a futurist?
That, at least, is my conclusion after reading an essay he wrote in 1931 titled “Fifty Years Hence,” various versions of which were published in MacLean’s, Strand, and Popular Mechanics. (Quotes to follow from the Strand edition.)
We’ll skip right over the unsurprising bit where he predicts the Internet—although the full consequences he foresaw (“The congregation of men in cities would become superfluous”) are far from coming true—in order to get to his thoughts on…
Energy
Just as sure as the Internet, to forward-looking thinkers of the 1930s, was nuclear power—and already they were most excited, not about fission, but fusion:
What could we do with all this energy?
I assume this was just an illustrative example, and he wasn’t literally proposing moving Ireland, but maybe I’m underestimating British-Irish rivalry?
Anyway, more importantly, Churchill points out what nuclear technology might do for nanomaterials:
Transportation:
And even farming with artificial light:
Biotech
Churchill also foresees genetic engineering:
Including lab-grown meat:
And artificial wombs:
Moral progress and risk
This last point is his segue from technological to social, political, and moral issues. The ability to “grow” people, he fears, could be used by the Communists to create human drone workers:
In the final paragraphs, he sounds a number of themes now common in the Effective Altruist community.
More than a decade before the nuclear bomb, he also expresses concern about existential risk:
He laments the inability of governance to deal with these problems:
More broadly, he laments the inadequacy of our evolutionary legacy to deal with them:
Which leads him, in the end, to call for differential progress:
I don’t recall Nick Bostrom citing Churchill, but I guess there’s nothing new under the sun.