[mr-ron]

I dont think the commenter is saying that they are lacking the bacteria. If they have a bacteria that feeds on lactose / milk, and they give pasteurized milk, ,it will promote growth of that bacteria.

Only if they dont have the bacteria at all would pasteurized made a difference.

[nerdponx]

But it's not even clear that the bacteria feeds on the milk. There could be other mechanisms of action for preventing or suppressing allergy.