Well, maybe less of an approximation and more of a safe lower bound. If I'm confident that the metaphysical criterion I'm concerned about begins sometime after birth but I'm not sure exactly when, I might suggest a legal threshold of birth to be on the safe side, as it might be infeasible and morally risky to evaluate individual infants on a case-by-case basis.
One argument is that birth is a practical, unambiguously observable cutoff that approximates some more slippery criterion like self-awareness. Even if you believe that self-awareness is the morally relevant threshold on a theoretical level, you might say birth as your answer because you think that's the best cutoff for society to use in practice.
There are forms of physicalism that are not eliminativist (they see consciousness as something real, for example as a kind of information processing) and are not epiphenomenalist (they hold that mental states can affect the physical world). I hold a view like this, and I would guess most non-dualist philosophers of mind do too.
Personally I think that eliminativism (at least in its most extreme forms) and epiphenomenalism are both intuitively implausible. They contradict my firsthand experience that my consciousness exists and has effects on the observable physical world. So I'm unlikely to accept either of them without a strong argument.
"Under physicalist epiphenomenalism (which is the standard approach to the mind-matter relation)" <- can you give support for this parenthetical claim? It has been some years since I took a philosophy of mind course, but when I did, I got the impression that epiphenomenalism is not the most popular view on the mind-body problem.
Before FTX collapsed, the company was aggressively marketing crypto, a highly speculative and volatile asset class, to unsophisticated retail investors. IMO this should have been a red flag, because it's a harmful career in the form of "Marketing and R&D for compulsive behaviours such as [...] gambling" from this list: https://80000hours.org/2015/08/what-are-the-10-most-harmful-jobs/ . This should have made the EA community apply more scrutiny towards SBF and FTX and avoid making him the public face of the movement as much as he was.
If I understand correctly, it sounds like you think the US and EU are more amenable to regulating AI than mainland China, Taiwan, or South Korea. Is that true? The US and some European countries are famous for valuing individual liberty, so on that basis I might guess they would be less amenable to regulation than East Asian countries. And this article seems to indicate that the Chinese government is already regulating AI more strictly than the US government is: https://www.theverge.com/2023/2/22/23609945/china-ai-chatbots-chatgpt-regulators-censorship
Points 1 and 4 suggest that donors interested in this type of work might want to fund more research to find effective interventions.