If it's proven beyond reasonable doubt in a court of law that BS is innocent of raping and assaulting two little girls under the age of 10, then so be it.
The court will not determine that BS is innocent beyond reasonable doubt. Prosecution need to prove that BS is guilty beyond reasonable doubt.
If the medical evidence is correct then there is no doubt that these girls were sexually abused. But a young child nominating a person as the perpetrator is not definitive proof of the guilt of that person. Children are notoriously susceptible to influence. Read this UK High Court judgment about two children claiming to have witnessed satanic cults:
https://www.judiciary.gov.uk/wp-content/uploads/2015/03/gareeva-dearman-2015.pdf
I am not suggesting that the children have lied about the perpetrator or that the mother forced them to lie. It could have been as simple as a mother, on seeing evidence of abuse, asking the girls "It was Bill, wasn't it?" If small kids have been threatened and another "offender" is suggested, then it is a very easy out to blame another person. And then that belief becomes so ingrained that the girls genuine believe the offender was Bill. This is not wild speculation on my part. This is a phenomenon that is widely acknowledge in psychology and also in the courts, where evidence of young children usually requires corroboration.
This was clearly a dysfunctional family where a convicted child sex offender was allowed to live with young children. I'm pretty sure that, upon discovering abuse, the mother did not leave the questioning of the girls to experts trained in appropriate questioning of young children. I am positive that, intentionally or unintentionally, the girls had suggestions put to them, especially if a mother just could not contemplate or comprehend that her brother had molested her children.
BS may be guilty. He may be innocent. I don't know. But the fact that the girls were very young and may have been subject to suggestion, they living with a known child offender at around the same time, I think is reasonable doubt as to the guilt of BS. Unless there is medical evidence that excludes H as a possible offender due to him being in prison, then prosecution do not have a very strong case against BS.
My opinion only.