They talk to the ship when they need something. They don’t ask Icarus II for its opinions or suggestions. Its sentience both reassuring and discomfiting, they prefer to ignore it watching them.
Icarus II sees Corazon and Cassie embracing, upright and fully dressed, when they crave the feel of another human. It sees Capa and Mace fighting for the same reason. It sees their attachment to the Earth and their families. Brains and hearts. It understands.
Icarus II filters out its predecessor’s distress signal before the crew hears it. Mission parameters wouldn’t accommodate the possibility of hearts shutting out brains.