The reason they use chemical names for the vitamins is that there are different chemicals they can come from. I don't know all of the details on this, but there are several chemicals that can provide vitamin A (the digestive process breaks down or converts them). Retinyl palmitate is primarily found in animal sources (a potential concern for vegans). Vitamin A also comes from several carotenes (alpha, beta, and gamma, specifically), usually found in plant sources. Alpha tocopherol is a form of vitamin E that comes from olive and sunflower oils. Gamma tocopherol is another form of vitamin E that comes from soybean and corn oils. I don't know what other vitamins have multiple forms like this, but I know that many do, and even minerals have multiple chemical forms.
Anyhow, the FDA requires specific chemical names to be used because of this. A good nutritionist would know this and might even know things like how well the body absorbs each. A dietitian might not know the specifics, but in my opinion, if she does not even know that vitamins have multiple chemicals sources, she is in the wrong profession. Don't even take it with a grain of salt. Ignore her "advice" completely, and trust the real nutritionists and dietitians employed by Soylent.
As far as the soy thing goes, I would not worry. In Japan, they have been consuming large quantities of soy for centuries, without any problems (just for the record, recent discoveries have shown that the lower average height of Japanese people is primarily caused by the fact that they live on an island, not because of diet). Yes, soy does contain estrogen mimicking chemicals, and when you feed rats more of these chemicals than the average human would consume in a lifetime, it can cause problems. What it comes down to is that even a diet of pure Soylent will provide less of these chemicals than a typical Japanese diet, and quite frankly, I am going to trust the thousands of years long "study," on a huge population (Japan) of real humans, at realistic rates of consumption, over a few very short studies, using a small number of rats, at absurd rates of consumption.
Studies like this are great for learning the possible uses of chemicals found in foods. They are horrible for choosing what you should eat. The only real risk found in any soy studies was that feeding infants soy formula exclusively (far more than even the average Japanese adult diet) could theoretically have negative side effects (I don't know of any cases where this has actually been observed). Given that you should not be feeding infants Soylent in the first place (and, I actually suspect that Soylent has significantly less soy than soy based infant formula), there is nothing worth being concerned about.