All poultry in USA is Hormone and antibiotic free by law. There are isolated abusers as with anything. They can administer Anitb to sick birds but only under Veterinarian supervision and quarantine. After birds are healthy, thay can be returned to stock, but the group must be random tested for residual Anitb.
A natural bird is one that has not been further processed. It is left in a whole muscle state of one kind and does not have anything added such as saline solution (marinade) or any forming etc....
Free Range are usually your best bet between Commercial poultry and Organic. Free Range birds (the minimum by law) only need to HAVE access to the outside for at least one hour per day. They DO NOT actually have to go outside ever.
The upcharge for organic is your personal decision. Remember Organic birds do not have to be FREE RANGE. Simply fed an organic diet.
The real key here is finding a grower/producer who's treatment of the birds represents your vision. (similar to the one in the article) If growing conditions are NOT a priority to you, then a Tyson natural bird is perfect. Petaluma Poultry in CA. is probably the single best large scale producer. Their birds are real 'yard birds'.
Personally, I can find a clear flavor and texture difference between a commodity bird and a quality free range bird. Now, the difference between Petaluma's Free Range and Organic is not so clear. That becomes a morality decision.
Bottom line, buy what tastes good and you feel ok with.
EDIT, some speeeling errors corrected