This was a completely pointless episode. I thought Phase 3 set up the fight between between Kira and Athrun for this episode, but no. That'll be happening in Phase 5. Phase 4 was a continuation of a huge theme in the Gundam mythos. "Why do we fight?"

To paraphrase Mu La Flaga it's hard to find anyone who fights for no reason. Kira realizes his reason to fight. Not to kill the enemy, but to protect. Kira's "normal" friends decide that they are tired of having him come in and save them so they volunteer to serve on the ship.

The episode ends with Kira catapulting off to face Athrun.