Although Tangs will eat meaty foods along with the other fish in the aquarium, it is important that they are offered plenty of marine based seaweed and algae. This will strengthen their immune system, reduce aggression and improve their overall health. Offer dried seaweed tied to a rock or use a veggie clip, and feed at least 3 times per week. Sea Veggies, Seaweed Salad and Ocean Nutrition are all ideal products and are very easy to use.
As long as they have algae to center their immune system it is fine for a tang to have meaty foods as well. I simply said by giving the tang a variety of diet it will ease stress levels and the feeling of being starved. I am not contradicting what you say, but Tangs will eat meaty foods when mixed with other species in captivity and I believe there must be chemistry within the artificial habitat.