Something that is so far removed from a normal Bachur’s mind is not considered ‘a mistake’. We are obviously coming from two different angles and you just don’t see it as so foreign. I see that from your description of what should be taken lightly.
Yes, it will depend on the norms. In my upbringing, something like this had a 7 mile barrier. It doesn’t get crossed by ‘mistake’. If you are talking about another society, the situation changes. This whole thread, as I said earlier, is theoretical, so we can create the setting of the story, ourself. I gave it a Chassidishe Yeshiva with a good Bachur. You seem not to relate to that. So, change the setting and I’ll agree whole heartedly!
On one point I can agree, though. After his initial scare there is no reason that they shouldn’t negotiate with him.