As a mother myself, I am mystified how a woman who clearly loves her son would want to live forever in a world where he will not exist, especially considering the reason he will not exist is because he will be killed by the same "loving" God that she is devoting her life to serving.
She may have convinced herself that it is entirely her own decision that has not been influenced by anyone, but if the Society changed their policy on shunning and said it was no longer necessary to carry out this barbaric practice, would she still have written that heartbreaking letter to her son? I personally doubt it.