If you look at the actual chemistry, this makes absolutely NO sense. Asorbic acid is a very simple molecule, and can only be asorbic acid if it is exactly 6 carbon atoms 8 hydrogen atoms and 6 oxygen atoms linked together in a specific manner. No other modification gives you asorbic acid and it cannot be missing any of these atoms and still be asorbic acid.
The asorbic acid made in a lab is chemically identical to that found in citrus. The only potential difference could be in the isotope ratios of carbon, oxygen, and hydrogen but that would not make a bichemical difference in how the body processes it. There are compounds found in vitamin C from natural sources that are not found in lab created asorbic acids, but they are essentailly impurities that are not removed in processing and are carried over from the fruit. They may be beneficial, but they are not part of the actual asorbic acid. Asorbic acid that is lab created contains only, or very close to only asorbic acid molecues. The missing compounds are not actually vitamin C at all, but other compounds found in the fruits.
I do agree about genetically modified produce. The sugars starches, protien ect are complex molecules that are being modified from thier natural versions, and those modfications are not good for us. They can be modified and still perform their basic intended function becuase they are so complex in structure, but that is also why modifcations to there structure that do not effect thier basic function can have unintended consequences. It is not a good idea to mess with their natural order and consuming as much as possible that is as nature intended is certianly a good idea.
I don't think however that many people really understand what "genetically modified" means and how it relates to compounds such as asorbic acid. Asorbic acid from genetically modified corn sugar does not contain any of the modified genetic material, only the carbon, hydrogen, and oxygen atoms that came from nature to make that sugar. Its stucture cannot be altered adn allow it to retain its identity so it is exactly the same as asorbic acid from any other source. It is not the same as a vitamin C supplement from a citris fruit, but that is not due to any differences in the vitamin itself, but due to what the vitamin is complexed with and what impurities are carried with it.
The problem with GMO food is that modifying these genes changes WHICH molecules cells are manufacturing, and in what quantities. The modified organisms contain fewer nutrients becuase their modified genetic code told them to focus one creating more starch to bulk up the product and increase yield rather than producing the vitamins that our bodies need. In some cases the modified genetic code also modifies the structure of the sugars, strarches, protiens, and fats the cells produce to increase yeild and or calorie content. It is all about business and selling more product at a better profit margin.