Either way, that’s not feigning surprise. Odd to call it that. What they are saying is when you are surprised somebody didn’t know something, don’t let it show.
The reason we call it "feigning surprise", is that the surprise is pretty rarely genuine. It's an interaction people have more-or-less-unthinkingly practiced throughout their lives to keep the out-group separated from the in-group
This is a sharply negative interpretation of behavior of people who may be acting genuinely, if without social grace. I think few people shocked that you don't know bash are displaying that surprise as a way to keep you in the out-group - I think they are surprised.
I would argue that the real in-group/out-group behavior is excluding people who aren't naturally adept at being social.
I know it was tongue in cheek, but to respond directly, intent doesn’t matter when the result is universally harmful. The recipient shouldn’t have to ignore the harm just because you didn’t mean anything by it. I can have the best possible intent when telling someone they are fat out of concern, but it doesn’t mean the result isn’t harmful.
FYI i’m slightly on the spectrum and it took me a very long time and destroyed a lot of relationships before I understood this. I used to believe similar, and even assumed good intentions most of the time. The problem is many people do not have good intentions a large percent of the time, and there were situations where I went years without realizing people were being extraordinarily mean to me who I thought were friends. either side of it, I just don’t think it’s a great philosophy.
The first time I ran into this was working at Meta, where that was one of the core values (it's since been replaced by "Be direct and respect your colleagues"). It was one of those slogans that sounded fine on paper, but in practice, it was almost exclusively weaponised by powerful folks to excuse their transgressions.
Think someone is sexually harassing you? You are clearly not assuming good intentions on their part. Think they are being racist towards you? Same thing. Think someone is sandbagging your promo for personal reasons? Ditto...
Your examples sort of underscore why “assume positive intent” matters a lot for how you engage but not a lot about what you engage on.
Working against the feigning surprise thing, if somebody says “oh I don’t know what DNS is”, the problem isn’t with offering to help them understand DNS, it’s leading in without projecting shock/alarm.
If somebody is blocking your promo, assuming positive intent doesn’t mean you just let them do it, it means you escalate by focusing on the root issue (“this person is affecting my promo and they’re not giving me any actionable signal as to why”), not speculating on their intent.
> Is being surprised somebody doesn't know something putting them down
Yes.
> is being unsurprised they are ignorant putting them down
Again, the whole reason to just declare this as a rule is so that you’re not put in a position to try to decide if somebody is ignorant or not. You set a social guideline, and if people break it, you point it out, and it doesn’t matter why they did it.
People doing that are doing it intentionally, and they aren't going to follow your rule.
People who are open to listening are not pretending to be surprised in order to put somebody down. They are actually surprised and (perhaps) unintentionally hurting somebody. If that somebody is hurt, they need to ask themselves which hurts more, having somebody surprised you didn't know something (aka they think you are smart), or being unsurprised you are ignorant of something (aka they think you don't know stuff).
Not usually, no. They haven't (for the most part) adopted gatekeeping behaviour just to be dicks, they've adopted it as a method of signalling to other members of the in-group that they too belong to the in-group.
From their perspective, the effect on the person in the out-group is merely collateral damage.
As akerl_ says, it's not telling you to assume anything. It's talking about behavior, not thoughts.
You can be thinking they're the most ignorant fool on the planet, or you can be thinking that a minute ago you believed them to be so smart, and now that image of them is shattered and you're disappointed...but all this is asking you to do is not to perform that surprise to them, regardless of whether or how much you feel it.