God’s anger is so great that He says He will destroy the Israelites and start again with Moses and his family. Moses entreaties God and begs him to change his mind. What will people say? That he took the Israelites out to kill them? That He was incapable of fulfilling His promise? In style, it is very similar to Abraham’s entreaty over Sodom and Gomorrah. How can the Judge of the Universe not do justice?
Of course, this and similar episodes are poetic. This is not a rational philosophy. It is an appeal to God’s mercy in which Moses repeats the thirteen qualities of Divine Mercy that he enumerated after the Golden Calf episode to similar effect. We do not deserve the forgiving God. We fail all the time. God’s mercy is a gift we take for granted but we should not.
The result is that God gives the Israelites a second chance as He has done after two temples were destroyed. But it also reflects on the morality and altruism of Moses. He put the people before himself. That is the mark of true leadership.