The belief in what's in the letter could explain some things like how the board couldn't trust Sam to keep this "discovery" at bay, and how it could be better to implode the company than let it explore said technology.
Nearly all leaders need to lead in areas outside of their backgrounds. That doesn’t meant they aren’t fit, that would be ridiculous. They just need to have the right team advising them and be good at making decisions based on available information.
Now, I’m not saying these particular board members were doing that, but that’s what a good leader does.
When adding Larry "My predictions didn't come true but I wasn't wrong" Summers to your board is supposed to be part of the solution, you may need to rethink your conception of the problem.
Under the arrangement at the time the board's duty was to the mission of "advance digital intelligence in the way that is most likely to benefit humanity as a whole."
Implied in that is that if it can't advance it in a way that is beneficial then it will not advance it at all. It's easy to imagine a situation where the board could feel their obligation to the mission is to blow up the company. There's nothing contradictory in that nor do they have to be ML experts to do it.
It's weird and surprising that this was the governance structure at all, and I'm sure it won't ever be again. But given that it was, there's nothing particularly broken about this outcome.
The belief in what's in the letter could explain some things like how the board couldn't trust Sam to keep this "discovery" at bay, and how it could be better to implode the company than let it explore said technology.