For the record I do not think the kid moved either BUT NO ONE can prove the kid didn't move!
We can never know for sure if the kid moved, but we do know for sure he won't ever rob an innocent person going about their business again!
We also know beyond a shadow of a doubt who instigated this deadly encounter.
Legally, self-defense is an affirmative defense and therefore one of the rare cases where the burden of proof actually shifts to the defense.
The defense has to prove the kid did something before the second shooting that made the pharmacist fear grave bodily harm. The prosecution doesn't have to prove the kid did not. For this reason, I would expect the pharmacist to take the stand. I don't know how else the defense can meet its burden.
In theory, anyway. You and I have already agreed the letter of the law may not matter to the jurors.