"We, who were nothing but systems, couldn't possibly have feelings of hatred or emotions."
Here we reconnect to the central conflict of the past: the fog was merely created to fight and isolate humanity, by someone or something. As to who or what I don't think that has been answered yet.
Right, Kirishima and Haruna are technically not part of the Blue Steel fleet, but are with Makie's faction, another human-aligned renegade faction of the Fog. They're just cooperating with him because they're on a mission to find out Gunzou's connection to the facility fire.
Provided they win this battle, I suppose the lesson here is that human intelligence > artificial intelligence.