He should have been charged.
Ever since Brandon Lee’s death filming The Crow, Hollywood stopped being quite so retarded and the prevailing wisdom was to treat blank firing guns as real weapons. In other words they NEVER get pointed at another person loaded or not. You have a non firing replica for scenes where someone needs a gun pointed at them and you fake the rest. Anyone not doing this does deserve to be charged for any injury they cause to someone else. Furthermore Alec Baldwin is not some new actor, he would have received literally hundreds of safety briefings on numerous productions over the course of his career. The live rounds is sheer incompetence but the way you film these things is by following the 4 rules of firearm safety. In other words at any time a live round should be able to be substituted with no loss of life or injury.
TL;DR: completely preventable death and everyone involved should go to jail.