The medication in medicated feed isn't a traditional antibiotic anyway. It is an anti-coccidiostat -- coccidia are protozoans kind of like amoebas. So, feeding medicated food won't help with traditional bacterial infections like some pneumonias.
Why would you treat them unless they are sick? I'd just remind this person that using antibiotics when they aren't necessary is a great way to breed resistance in the germs. Reminds me of a lady I used to work with who ran to the doctor and insisted on antibiotics every time she caught the common cold, which is a virus.
Now, I hatched a button quail last friday that was really struggling, barely alive for a couple of days, and I have used tetracycline on it all week to ensure it doesn't get a secondary infection. It's doing much, much better now and should make it. I'll continue the tetracycline another 3 or 4 days then quit it. But that was for a specific reason.
I don't think most commercial poultry growers even use prophylactic antibiotics anymore. At least I hope they don't.