Why do you call it my scenario? What I or anyone else thinks about it is irrelevant. The truth is what it is.
Terri's blood tests showed lactic acidosis, an abnormal blood chemistry caused by violent exertion in the absence of oxygen. One may infer that she fought for a breath of air with everything she had. But it would have been hopeless with a man twice her size on her back, pinning her down.
That's one interpretation....I explained it 3 years ago on FR.
Now, how do we get Michael to confess?