In my opinion, if they eat any type of prepared food at the LFS
it should be ok. You can wean him onto a larger assortment of frozen when you get him.
Now, if the fish show NO interest in the food I would be hesitant. My Mandy didnt' actually eat when I saw her at the LFS
but she was interested in the frozen food he put in, swam up to it and checked it out and kinda looked like she was gonna eat some. If you have a decent pod population you might be ok in that case. Not sure if i would take the gamble i did with mine again, so I'm not really sure what my opinion on this is. LOL
Either way GOOD LUCK! I know in the end you'll make the right decision for you and the fish.