He didn't venture into any of the maths of the bullet trajectories but I suspect he knew perfectly well what had most probably happened. The issue is that it doesn't prove anything because it's all about possibilities and probabilities and the more precise you become about something (as we have done in our post) the more you leave yourself open to easy criticism which might have undermined (his) more credible evidence. In this instance, just a fractional change in the rehanging of the door can change every calculation and hence trajectory. Funnily enough, this doesn't matter but the explanation would become a lot more complex if you had to explain why in court.*I wondered more what he was getting at with his comment
I agree with your post which I already read.
* For those that are curious: two bullets travel through the larger panel (A, B) and two through the smaller panel (C, D). This means that the relative trajectories of bullets which travel through the same panel remain meaningful regardless of what the actual trajectories are and regardless of how the door is hung or panels repositioned. Apply any trajectory to where Oscar says he stood and, allowing that bullet A must be the first bullet fired, you are left with a trajectory for bullet B that implies that in all probability he must have moved forwards. However, it's still a minefield because there are still deflections through the door to be factored in and, in all but one case, these weren't measured.