Thats the point. The torture served as a reminder for Moira to take into her next 7-8 lives to deter her from working against the greater good of mutantkind. Destiny let it be known that if she didnt, that she would find her and do worse. Simply shooting Moira in the head wouldnt have had the same impact
Lord Ewing *Praise His name! Uplift Him in song!* Your divine works will be remembered and glorified in worship for all eternity. Amen!