Although Eliezer didn’t put it precisely in these terms, he was sort of suggesting that if one could self-modify in such a way that it became impossible to break a certain sort of absolutely binding promise, it would be good to modify oneself in that way, even though it would mean that if the situation actually came up where you had to break the promise or let the world perish, you would have to let the world perish.
Although Eliezer didn’t put it precisely in these terms, he was sort of suggesting that if one could self-modify in such a way that it became impossible to break a certain sort of absolutely binding promise, it would be good to modify oneself in that way, even though it would mean that if the situation actually came up where you had to break the promise or let the world perish, you would have to let the world perish.
I think the article you (and the parent comment) are talking about is this one