I've no more idea than you have - sticking a child in prison with other criminals has never seemed a logical way of rehabilitating them.
He re-offended, therefore he was not rehabilitated - wherever he was.
Are you proposing that they dispose of one and see what happens with the other - rather like a lab experiment?
No, they are your words, not mine. I'm not aware of having proposed anything of that nature.
Nothing will alter the fact that these were ten year old children when they committed their crimes
They aren't now, and yet Venables is apparently still a danger to children. No-one has pretended they were adults. They were ten, and now they're not - they are the same people though, and Venables has demonstrated beyond doubt that his freedom was a bad idea.