If you're interested in Soylent then buy some. Try it for a meal or three. Read a few reviews of other people who have tried it. If it works for you maybe try it a few more meals... take care of yourself. If you're concerned about the safety of the product then don't buy it.
Bottom line, as a consumer, manage your own risk vs. reward. This is a product you can buy cheaply and experiment with to find out if it's right for your needs.