larry - of course you are posting here on this thread at my invitation - and I am glad that we're not having this debate over on the support thread.
I meant in general that I couldn't understand why you'd want to post in the Feminist section.
The thing is, for me as a feminist it's not about being "correct" as in your "my views have proved to be correct" statement.
That's quite a male construct: win/lose - correct/incorrect - let's work towards win/win and change the world. 
I hope that OP's family are offered counselling. I am sure that the investigation has to be conducted first.
If there are shortcomings in the authorities response to this situation/these types of situations then let's campaign to change them.
I think I can sense your concern for the OP etc and your suggestion of the psychiatric counselling is valid.
However rather than walking away from this thread feeling "right" - I do hope that you can question your attitudes a bit in the face of the overwhelming upset at you saying;
" I am hoping it is far MORE innocent than the bald statement shows. Thirteen year olds vary hugely, from the sexually active to some who are really still children" and
"You are completely ignoring the fact that the "abuser" is the 13 year old SON of the OP. It is not pleasant to think about sexual abuse but the black and white term makes no distinction between rape and a game of doctors and nurses. Yes, 13 is a bit old for that kind of thing, but 13 year olds are wildly different in development."
You will claim that I/other posters have ignored your "nuances"
and the subjunctive etc but actually:
There are no nuances - sexual assult is sexual assult - rape is rape. A central principle is "I believe you".
The poster's DD said clearly, very clearly for a 6 year old that her brother had assulted her.
So very very clearly that I found your posts disgusting.
Now maybe it was because you'd not read the posts properly - but I suspect that as a man you were "giving the benefit of the doubt to the abuser".
Although I do not know how much clearer it could have been:
I will repeat what OP said:
"She just said that her 13yr old half Brother keeps pulling her trousers and knickers down and looking at her privates and has touched her(haven't asked her how). And when she is led on his bed he puts her knickers over her head so that his face is close to her privates."
In fact then the boy admits this to his mother - and that was all before your posts.
Raising awareness of the seriousness of sexual assult and rape against women and children is hugely important.
I am trying to challenge your attitudes larry but far far more importantly the 100s of other poster and 1000s of lurkers who have had similar things happen to them and dismissed - it's important to see your attitde challenged.
BTW - in the real world your attitude is of course the prevailing one.