To get them to eat something. Better feed them now then wait much longer to find something to feed the ghost shrimp. Not saying you shouldn't gut load them, but that shouldn't be your #1 priority, and definitely shouldn't hold you back from feeding them.
Keep in mind, they basically have 0 nutrition (mostly water), unless they are fed 1st. You could even ask the shop to toss in some flakes for them to eat on the way home, in the bag.
well i know hes eating now he took down a two inch fiddler that i thought died becuase i could never find it and he ate the legs and took bites out of it so ill be getting some ghost shrimp right away