No, it's NOT the same. A mother covering for her son by strangling her own daughter using a garotte (or by any other means, actually) is in itself beyond bizarre. When we add to that the writing of a ransom note, it simply makes no sense, because by staging a kidnapping there is no need to stage a perverted sexual attack. One or the other might possibly make some sense, but both? Sorry, does not compute. Then on top of all this, we must believe that a 9 year old child was sexually active enough to produce the vaginal injuries? That piles one bizarre theory on top of another.
This is truly an off the wall theory on top of an off the wall theory, taken seriously only because the authorities were desperate for some sort of explanation, given that John, the most likely suspect by far, had been "ruled out."
If we rule John back in then we see a scenario that any experienced profiler would recognize. Father-daughter incense followed by murder to avoid exposure. Maybe he thought she would tell, maybe he was afraid her doctor would report the vaginal trauma. The "garotte" could be explained as a sexual device (ala Wecht) or as a means of finishing her off after the head blow by facilitating ligature strangulation (possibly to avoid leaving prints).
Horrible and disgusting, yes. Bizarre? no. Unbelievable? No.