Is it wrong to think that it is ridiculous that my 4 year old nephew still eats pureed fruits and vegetables?

My sister has a very picky eater on her hands. For awhile she was doing the "sit here until you eat it or go to bed without dinner." She did this for a week or two and claimed she was afraid he wasn't getting the nutrition he needs and was losing weight. He was absolutely stubborn and would sit there for an hour or so, and then go to bed with nothing. Now she has started this new things...she puts a vegetable on his plate in it's true form how the rest of the family is eating it, and then next to it she puts the same vegetable, but pureed (or a veggie mix, pureed). She tells him he has to eat one or the other, he always eats the pureed. Or she gets the pureed Gerber veggies still and gives them to him as snacks. She puts pureed veggies in his spaghetti sauce, homemade pizza sauce, etc. Same with fruit, the only fruits he will eat in their true form are bananas and sometimes strawberries. So she makes him smoothies, or gives him V8 Fusion once a day and then sometimes gives him the pureed Gerber fruits for snacks. Am I wrong to think this is absolutely ridiculous? Shouldn't he be being forced to eat the vegetables how they are given to him, and not bending over backwards to please him. He's going to be spoiled, what's he going to do when he's 16, whip out some pureed vegetables in his packed lunch at school? How can I approach her about this?