Well the Pros. case is based on where the casings were and the earwitnesses etc.
This all indicates that a single shot from the entrance into the bathroom, apparently hit Reeva. Then the 17 minute gap--think of the 5th OP's phone now, not the diversionary Reeva phone--then a rapid set of 3 final shots.
So your scenario does not fit a single final volley.
That commenter was intelligently finding a way to see how OP knew exactly where she was when he fired the final volley. But there could be other ways how OP knew where she was for the final volley, if Pros version is true.
I wonder with all the recent influx of reports , documentaries, re-enactments of OP's version , why is the withholding of extremely important evidence, the phone he used after the killing never mentioned by either side.
OP or his defence did not hand this over to the investigation officer, yet they will criticise the police for this,that and the other. IMO the with- holding of this phone is a greater impediment of justice than any mistakes the police made because it was intentional.
They will gloss over as unimportant the phones found on the Bathroom floor with a mild dismissive comment but in all these reports where is the mention of the 5th phone. IMO this is proof of who really is behind these reports since anything detrimental to OP seems to be taboo.