@mrherewriting
but I can tell him he doesn't need to ask because he doesn't.
You have no idea, you don't know that story in full. And still think you're the only one who knows right from wrong. You don't.
Not related to the OP, but to advance the discussion... it's a rather theoretical example (even if based on a "true story"), and I'm a total pervert, so please bear with me:
It's a Sunday afternoon during a national holiday. An extended family and friends are celebrating a birthday in a country house. Just before the cake, a girl, let's name her Alice, discovers she has a tick biting on her. Ticks in the area carry a number of nasty diseases; the infection chance of several is proportional to the time the tick hangs on, so it is paramount to take it off as soon as possible and do it with the proper care.
However, the closest medical service facility possibly available at the time is over fifty miles away. Alice can't drive, someone else would have to go with her. It would be a major disruption for the party, several hours round trip even not counting possible wait time at the facility, and that's if the service is at all available there. Even if so, there's little trust in the holiday crew they might find there, and Alice is especially disturbed about that for where the tick is on her.
There is a person onsite who can take the tick off immediately. John is a good boy scout and outdoorsman with steady hands renowned for precision in micro motions and has done just that on several occasions, from himself and others. He may say he's not at all that experienced in that, but agree it could be no problem without much pressure... before learning the exact details. But Alice knows and trusts him, and may have asked him to do it herself, and what's all the fuss really about? It's just a tick.
So it's a bit of an ambush in an upstairs bedroom full of women, to discover the damn arachnid is sucking in on the inside edge of Alice's outer labia lip. John mentally distances himself and sets to work under watchful eyes of Alice's older sister Mandy, their mother, his own mother and even the aunt Hanna, all determined to preserve Alice's honor despite the circumstances.
John has no special tools with him and opt to try to take the tick off using a thread loop. Unfortunately, the thread he's provided with is a bit thick and curls easily so to tie the knot around the snot of the tick, deep into the soft flesh takes many tries.
Now, if it was Alice's own [threshold_age] birthday we are celebrating, and John is older, (say, by two years), there's no limitations at all on what and how we could describe.
Like,
Exactly how Alice partly disrobed to reveal the problem to John, what exactly John saw in high resolution and vivid color, what moral struggles, if any, he had before continuing with the task he had taken on, exactly how he stumbled around in the not at all trivial place with it, what his inner monologue was throughout, even how he inadvertently, or not at all inadvertently, gave Alice an orgasm in the process.
How exactly Alice discovered that tick in that place at that time, her anxiety and struggles about the situation, what exactly she thought about John going after the tick there, how she revealed herself, how his fingers felt, how she tried to hide her orgasm from the moms watching on.
How Alice's sister Mandy saw the whole situation, was she jealous, did she fantasize about John's fingers on and in her own cunt, or just distraught and appalled.
Or was it Hanna who struggled to reconcile what she saw regarding Alice as much too young and yet been turned on herself. Or one of the moms.
What Alice's virgin boyfriend imagined happening in the room after overhearing partial conversation between the women mentioning the place of the tick.
What Alice's dad feared after being dutifully informed about the situation.
Or how Hanna's boyfriend Pedro fantasized where the tick could be and how he would go around taking it off while touching the girl in all the wrong ways.
And who of all of them masturbated when and where and how furiously afterwards, and even continue with full on sex between John and Alice the same night, before or after taking her boyfriend, dad, or Pedro, etc, etc, etc.
We couldn't do much if anything of it very well if we had Compelling Plot Reasons (β’) for the exact scene to unfold exactly two weeks before Alice's [threshold_age] birthday.
Yes, I hear the screaming already, oh no, just don't go there, there's a million ways to work around it. Sure. And I won't if I used this scene in a story (I may, someday).
However,
The scene doesn't need to be sexual, at all. It could as well be coldly clinical. There's uncountable variety of other reasons the scene could be in a story besides establishing sexual relationship between Alice and John or whomever, not right away anyways.
It might be there just to reveal someone's character, or even to explicitly establish that John doesn't see Alice as a potential object of sexual desires, or to give Alice a psychological trauma, or advance non-sexual relationships between any characters present in either way, like, perhaps that how the friendship between the respective moms ended.
The whole point might be for Alice to contract Lyme disease, perhaps because John fucked up and squeezed the bug, not realizing, and the early signs went unnoticed because of the peculiar place of the bite, so it wasn't discovered before becoming chronic condition.
Nothing of that really demands the girl to be too young, even most moral struggles about inappropriate ages could easily be framed using strictly internal to the character or external locally legal [threshold_age+X] limit instead.
But for the sake of discussion,
The Compelling Plot Reasons (β’) for the exact age would ostensibly be unrelated to this situation, if for no other reason than for most directly related reasons to fall under prohibition anything. But would they all?
Secondary situations could be affected too. If Mandy decided to thank John in a very special way, wouldn't the very fact be implying she's been turned on by the scene rendering it questionable?
Or if the mutual embarrassment experience would eventually bring Alice and John together, possibly years later?
Or if Hanna would dump Pedro based on his reaction to her relating the curious situation, even if in an already sanitized form?
And back in the temporary doctor's office, what if John's indeed a medical student or even practicing MD, would a dry medical language allow more detail?
And anyway, while we probably could do most possible stories with minimal details, what exact details are appropriate for with scenario?
It's not at all clear cut, especially if the details seem innocuous and necessary for the author.