From a religious POV, God saved SABs brother because there's more to his life on earth still.
I do see why it's upsetting, but as an example I have a friend who is about to lose her toddler to cancer. She's at peace with the situation, she knows that God has a plan and the situation is greater than she or anyone can comprehend. She cherishes the experience she's had and how her family have grown through it, all the things her 3yo has taught her about life, faith and love. She knows in her heart she will be with her daughter again soon.
So while we don't know why right now, we will some day.