I can see the logic of trying to persuade the FDA that manufacturing is going well and is not the cause of any problems.
But attempting to draw the conclusion that manufacturing is stable from the fact that all manufacturing lots have equally wide patient-to-patient seems preposterous to me.
"We know the manufacturing is repeatable because we get the same wild variation in response no mater which lot we use."
Wild variation in response simply means that something is out of control and we don't know what it is. It doesn't suggest manufacturing is repeatable or stable.
It seems to me unlikely that the FDA would buy that argument. But maybe there are other details in the mix and the conclusion is not drawn as the slide seems to suggest. Perhaps the argumet to the FDA is made with detailed measurements on each lot.
On the other hand, maybe the FDA will but that argument.