What he is refering to but seems he doesn't have a full grasp of it though, is BAS
Basic Allowance for Subsistence (BAS)
BAS is meant to offset costs for a member's meals. This allowance is based in the historic origins of the military in which the military provided room and board (or rations) as part of a member's pay. This allowance is not intended to offset the costs of meals for family members.
Beginning on January 1 2002, all enlisted members get full BAS, but pay for their meals (including those provided by the government). This is the culmination of the BAS Reform transition period.
Because BAS is intended to provide meals for the service member, its level is linked to the price of food. Therefore, each year it is adjusted based upon the increase of the price of food as measured by the USDA food cost index. This is why the increase to BAS will not necessarily be the same percentage as that applied to the increase in the pay table, as annual pay raises are linked to the increase of private sector wages.
Because members are assigned to a variety of situations, some of which either mandate or prevent obtaining meals from a government facility, there are two types of BAS, each based on a differing personal circumstance.
So when he said she is being deducted pay for her food while on a ship, he is kind of correct. She really isn't having her pay deducted for food while aboard ship. In reality she is just not recieving her BAS since rations are provided for her at no cost while onboard the ship.
Hope this clears things up for you.