Chris Leong

A few thoughts:
a) "Rejected or never heard back at the first stage and left confused" - if someone clearly isn't good cultural fit, then identifying this at the first stage is the ideal outcome as it saves the time of both parties.
b) "Rejected at the final stage having wasted lots of time without useful feedback" - unfortunately, if someone is a bad cultural fit, then it's hard to provide feedback without coming off as rude. Additionally, it's hard to provide any feedback on this at all without making it easier for candidates to hide their lack of cultural fit.
c) "Many of the “unicorns” fall into one of two buckets with very few of the people I’ve spoken to falling in the middle. Many also swap between buckets without consistency" - Honestly, I'd take wrapping between the buckets without consistency as a red flag rather than a sign that the selectors were wrong. After all, in this case they seem to have failed both the immediate gut check and the more considered reflection of people who wanted to be open minded.
d) "It also seems like many orgs want ops people (even those on the hard ops side) to have excellent AIS knowledge and fluency, even though this is not required for the role" - I think there's a lot of benefits of having a unified organisational culture so you're all rowing in the same direction. If you hire someone who is only suited for a particular role, then you have less flexibilty in the future to promote them into other roles. You're also providing them with an implicit endorsement which may lead to them being hired into roles they'd be unsuited for in the future by other folks.
e) "A few hiring managers I’ve spoken to are very wary of hiring senior folks who haven’t come from EA/ rat circles citing individual bad experiences with such people. This feels pretty uncharitable given how many bad students there are compared to the few good students who get hired" - Is it charitable to dismiss the accounts of folks who wanted to be open minded and tried hiring such folks and then learned lessons from it? I'm not saying these hires can't work, just that the reasons for why they may not work are very subtle and I'd be much more enthuastic about your project if you were better able to steelman the opposing perspective (see also Chesterton's Fence).
f) "While it is true a bad senior hire can be more expensive than a bad junior hire, we can get far more information about the track record of senior people from their experience." - that doesn't really help if the issue is that the candidate is highly competent, but a poor cultural fit.
g) "Frustratingly, lots of these candidates do well/ are silver medalists in hiring rounds and are never passed on anywhere else" - If a candidate was just not quite good enough to land the role, you might want to pass them on. On the other hand, if a candidate is a poor culture fit, you definitely wouldn't want to pass them on.
h) "I would push these people to consider whether increased legibility of AI Safety due to recent warning shots and political salience could unlock much faster transitions that we aren’t capitalising on" - warning shots likely helps because it reduces the epistemic distance between the AIS community and the rest of the world, but I'm unsure why you think political salience would help rather than hurt. I tend to agree with Eliezer that Politics is the Mindkiller.
i) "Most of these people have done several BlueDot courses" - I've also facilitated for BlueDot. These courses do a lot of things well, but we shouldn't be expecting these courses to be fixing the problem of cultural fit. Cultural fit is the kind of thing that is hard to address with an online format. I expect BlueDot's Context Week is much more likely to be the right format for this. I also agree that local hubs are a good way of supporting this (I'm trying to do what I can at the Sydney AI Safety Space).
i) Despite everything I've said, seeing how many rounds closed without a hire suggests that we desperately need more talent and so I really do hope your project goes well, even if I think the challenge is much harder than you anticipate. Feel free to reach out if I can assist in any way.