To some extent, Hendry drew his conclusions on the basis of what is most likely as opposed to what theoretically might be possible. It is possible, in theory, that the jacket could have been on the floor and somehow picked up bloodstains consistent with it being worn during the attack and used to drag the victim. It is possible, in theory, that someone with an immensely muscular forearm could have stood in front of Meredith, inserted a large kitchen knife about halfway into her neck, and made a lateral cut that perfectly imitated the kind of wound that would be made by an assailant holding her from behind and cutting with a smaller knife plunged in up to the hilt. But, each of these possibilities is less likely than a different, more likely hypothesis. And the way to test the hypotheses that seem most likely is by placing them in a narrative timeline. Does each proposed element fit into the narrative? With Hendry's analysis, it does. It's not arbitrary, or one interpretation among several that are reasonable. It is very specific. I spent hours quizzing this guy. His analysis makes sense.
I don't for one second believe Guede had any interest in helping the victim he had just fatally wounded. The towels were not wrapped around her neck. One was found next to her body, and another was found beneath her body along with a pillow. Putting a pillow under Meredith's buttocks did nothing to help her, but it may have facilitated a sexual assault.