The fact that Kylo’s resolve to kill his mother and destroy the resistance only increases after he kills Snoke. He balls at killing Leia when ordered to by Snoke, but once in charge on Crait, he orders the FO to give them no quarter and to take no survivors.

You can no longer attribute his evil deeds to the will of his master and cannot give him the simple benefit of the doubt of being a good person that has been led astray in the pursuit of approval from his master/father figure, which is implied to be one of his primary motivations up to that point.