I would be amazed if Scott Alexander has not used "I won't socially kill you" at some point. Certainly he's used some phrase along the line of "people who won't socially kill me".

...and in fact, I checked and the original article has basically the meaning I would have expected: "knowing that even if you make a mistake, it won't socially kill you.". That particular phrase was pretty much lifted, just with the object changed.