I used to work for a charity that provided two free peices of fruit to each primary school kid in Edinburgh as well as setting up food co-operatives so that people on lower incomes could have access to fresh fruit and veg. Part of that was going into schools to get kids to try fruit, we used to make smoothies, kebabs etc...
It really shocked me how many 5-6 year old kids had never even tried a banana let alone the more exotic stuff!
Its a real struggle to get kids to try something new, but you've got to keep trying the food regulalry, kids taste buds actually change every 3-6 months, so foods refused initally may be liked a few months later. Perseverance is the key!
Personally, i believe this kid has an eating disorder, the treatment should be the same as annorexia, where the danger to health is treated first!