What Dixon did explain quite well was the splinters in Reeva's right arm and the distance and position her arm had to be in behind the door to receive the splinters to her skin. IIRC According to Dixon's investigation Reeva was standing very close to the door, 6-10 cm, at 20 cm the splinters would not penetrate the skin. Reeva had splinters in the upper and lower outer portions of her arm extending away from the elbow.
Looking at his positioning to demonstrate for the court, his right arm is acoss his stomach with the arm extended towards his left hip and his elbow bent. IMO it is likely Reeva was holding the door handle with (at least) her right hand, for safety just in case OP managed to open the lock or physically open the door open. I like that he did the tests to determine that, it gives a clearer picture.