Asgore never came out of New Home. He hurt a lot of his people, if only to save them. "I'm sorry." Toriel was right, revenge wasn't the right option and because he was a coward, many monsters will never see the light of day.
The justice system did allow a few monsters to go to their reform program, but kept the supposed dangerous monsters away. This included the majority of the Royal Guard. At least he was able to claim Undyne as a citizen underground so she wouldn't go to prison above ground.
Asgore wanted to end it, but he had to keep hope for his people, since it seemed a majority was lost.