Up to your GM/Table really.
Did the player take the Stunt with the understanding that it would? Does the GM feel it's a bit too powerful if it does?
Personally, I wouldn't allow Calm Blue Ocean to affect Hunger as a GM. However, I would certainly be fine with a custom Stunt - based on Calm Blue Ocean - to be taken that only affects Hunger. I just wouldn't let the one stunt do double-duty. But I am a less permissive GM in that sense, other GMs would be totally fine with it. The support for that would be page 190 "Highly stressful or emotional situations can still trigger your need to feed" (main book). Suggesting Hunger is emotional.