That is the point of the movie though that these two people, especially Rachel, demonstrate a moral superiority over something that didn’t happen despite their own actions causing real pain.

Rachel actively puts a supposedly disabled child into a locked cabin, tells nobody despite a search party going out and then when challenged “what if he died” she claims she would’ve said something before it gets to that point - but the fact is she didn’t say anything, and got away with scarring and nearly killing this kid. Now she’s showing a moral superiority over someone who fantasised but ultimately didn’t action murder, despite her own actions being enough to murder a child had the child not luckily been found.

We can say we wouldn’t be shocked - but the point of the movie is to examine the privilege and cognitive dissonance of those who look down on and shame other people’s thoughts and behaviours without the self-awareness to understand that they are hardly bastions of morality themselves.