Your son's behavior is 100% normal and any therapist with experience in male CSA issues would confirm that. The good news here is that the perp's lawyer is clearly not knowledgable in such cases; the defense he is proposing is nonsense.

Much love,

Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me.
(Woody Guthrie)