While I know very little about these traditions, it's my understanding from the article and briefly googling that the sewing of the mouth shut is the main part of the ritual. It's not about not getting bitten - the point is for the snake to die slowly in agony from starvation, thus "inducing" these same feelings in the person the snake was linked to via the items in the mouth in the ritual. Without the torture induced in the animal by the sewing of the mouth, linking the person to the snake wouldn't create the desired pain in the target. Of course, as I said, the only things I know about this are from the article and a couple links on google so this is just my understanding of what is already only really a theory.
That said, I'm so glad she's doing ok!