Maybe a late reply, but in this artist's perspective, when ship girls enter dock, they have their wounds healed along with their memories reset. Hiei seems to reject going to the dock herself (as you can see her clothes are still dirty) because she want to keep her current feeling towards Kongo.
Ikezaki Misa But despite that...The eventualities of weapons that learned to love....aren't supposed to know about love....that I can love Onee-sama like this.But despite that,......that weapons like us...I am happy from the bottom of my heart...