I posted your question on another Carnival site and got this answer:
The Spirit does not tender in Kahalui, Maui; she is docked at the pier over night and guests are free to come and go as they please. The confusion may come from another sailing date (5/2/08) when the Spirit sails and overnights at Lahaina, Maui- on this sailing the ship tenders and the tenders stop running at 10:30pm.
Stephanie
Carnival Cruise Lines Staff