This situation that you have posted here applies to many people. A young girl that I am very close to (six yrs old) has a similar problem. She won't eat anything except saltines, bananas, Chocolate muffins(her mother hides veggies inside), french fries & some kinds of cheese.
She loves goat milk (expensive as hell in the US). She just now started eating apple slices. She drinks some fruit juice and her mother puts vitamin supplements in. Everybody has been worried about her health but she's healthy as a horse. She loves animals and has said she will never eat an animal.
In fact, she
refuses to sit at the table when the family is eating meat. She tested with a very high IQ. She's very artistic, loves music and athletics. She's very anxious yet very loving and lovable. She's not Autistic but shows some symptoms.
She's a tiny female Morrissey
I don't know what to make of it all and I'm constantly amazed by this life. It's obvious that it is easier for some humans to cry, "Meat is Murder" than others. I agree with what you posted that parents should not force kids to eat things they do not like. It's all very interesting and I think most kids will expand their food spectrum as they get older.