[Yamer]

I took Arnold's plan as compassion and him wiping the slate clean. He knew he couldn't leave the hosts alive with Robert. He thought that by having Delores and Teddy go on an insane murder rampage it would end all hope of the park. He also put each host out of harm's way by killing them and not leaving them to Ford's fate.

Ford suffered a loss, continued with his dream despite, and locked every host back inside his own dream of denial. It took time, but Ford eventually realized the implications of the reality he created (aka hosts gaining sentience and self-actualization). He knew that they were all locked inside what he created, so he had to bide his time for the grand overthrow we saw in the final scene.

Ford created the hosts, hosts destroyed Ford, hosts inherit the park.

Also, I thought Ford's name for his new narrative was a clever play on words. Journey into Night...Journey in, tonight.