“digital penetration and sexual contact”
Interesting no penile penetration. Many pedophiles have attempted this (disgusting as that sounds). Given that the killer knew that JonBenet was going to be murdered, why would he care if he tore her in sexual intercourse? If it's vengeance, the more pain that JonBenet suffers the better I assume.
If there is sexual molestation, it is more likely the perp wanted to do it in a way that it would not cause any permanent damage that would be visible. Such an action would be something more in line with a family member, teacher or close friend.