The whole point of making it a rule is so those people can learn it and avoid accidentally putting other people 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.
If I say it's a social guideline to not tell somebody about something wrong with their outfit unless they can fix it in under 5 minutes, I'm not suggesting you go around assuming that everybody knows they have a stain on their shirt. I'm telling you it's net-negative to point it out to them.