"I find the characterization of a 10 year old boy as a potential abuser deeply problematic."
He is a potential abuser.
You can't surely be saying that it is impossible that a ten year old boy would abuse a younger child?
Some ten year olds are starting (very innocent) explorations of kissing, sexual display, touching.
As I said earlier, an old boyfriend of mine and a childhood friend of his thought they had sex when they were 9. What they did is not clear, but in involved genitals.
If the girl had been 5 years younger rather than a peer, what happened would have been abusive.
The disparity in size, strength, development and understanding would turn something innocent into something exploitative.
That's why both children are vulnerable here.
They are not siblings or cousins with a longstanding relationship.
Leaving them unsupervised together in a bed for hours is not on.
On the most basic level, presuming there is nothing sexual happening, it is not fair to ask a ten year old to have no privacy in front of a much younger, non-related child.