I've been disparaging Sam and OpenAI a fair amount in this thread, but I find it plausible that Sam didn't know.
I remember a job a few years ago where they sent me employment paperwork that was for a very different position than the one I was hired for. (I ended up signing it anyways after a few minor changes, because I liked it better than the paperwork I expected to see.)
If OpenAI is a "move fast and break things" sort of organization, I expect they're shuffling a lot of paperwork that Sam isn't co-signing on. I doubt Sam's attitude towards paperwork is fundamentally different from yours or mine.
If Sam didn't know, however, that doesn't exactly reflect well on OpenAI. As Jan put it: "Act with gravitas appropriate for what you're building." https://news.ycombinator.com/item?id=40391412 IMO this incident should underscore Jan's point.
Accidentally silencing ex-employees is not what safety culture looks like at all. They've got to start hiring experts and reading books. It's a long slog ahead.
I don’t expect Sam to know every detail as CEO. But this particular clause is very impactful and something that the CEO of a startup would have had to sign off on rather than some underling making the decision on their own.