It's very, very subjective, and alas the only way any one will know if they shouldn't have seen the body is if they go and see the body. There's no knowing how anyone will feel.
When my mum died, I saw her within the hour. She'd collapsed at home and was lying where she'd slumped. She looked terrible compared to what she looked like when I saw her the day before, standing in the kitchen making coffee like she'd done in that kitchen since 1969. No one knew death was hours away.
She was not alone when it happened, and I was contacted immediately. I have a photo of her which I took soon after she passed, and for me I will forever hold it dear. I am so glad I took it, despite her looking far from her best.
However, she was embalmed, and when I saw her several weeks later at the funeral home, she looked exactly like she did when I saw her soon after she died. So, in her case, it was not the time that had passed which caused an issue, it was how she looked when she died.
The thing which upset me most (and it was merely a sadness more than anything else) were the clothes they had dressed her in. I was not responsible for the choice, and the relative who chose them may not have realised her blouse was very much an "every day" blouse she wore a lot, as opposed to everything else she had in the wardrobe.
I was ok with it all. Another relative was hysterical. There is no knowing who will react and how. It is your job OP to support the choices of those involved. Unless professionals have deemed it an unpleasant process due to the state of the body upon death, you cannot advise them which way to go.