He's off at a tangent. It's not the fact that the orange juice comes in a carton - he could squeeze it himself and it would still be bad for him.
Let me try to explain what I've told him several times.
Sucrose is 50/50 Glucose and Fructose. Fruit is fructose. Glucose hits your mouth and starts being digested straight away. Fructose can only be digested by the liver. If you take in fructose without fibre it hits your liver when everything else does - the liver is busy and it puts it to one side to deal with later - and unless you've just done a huge workout it will turn it into fat - because there is plenty of energy knocking around from all the other food.
If you eat whole fruit - which doesn't taste as sweet as the juice - then the fibre takes the fructose with it to the intestine - 22 feet of slowing it down - and the liver has dealt with the meal and has the time to deal with the fructose and use it for energy.
I'm reading Fat Chance: The bitter truth about sugar by Dr. Robert Lustig. He deals with paediatric obesity. You can watch him talking about fructose on you tube - Sugar the Elephant in the Kitchen and Sugar: the Bitter Truth. He's very personable and understandable.
I picked him up at first from www.dietdoctor.com