"Soylent is a food product (classified as a food, not a supplement, by the FDA) designed for use as a staple meal by all adults." -https://www.soylent.com/about/
"Soylent is designed as a simple staple food, and people incorporate it into their lives to varying degrees. Some people use it almost exclusively, while others use it 2-3 times per week. There is no right or wrong amount of Soylent to eat - the whole idea is to find a balance that works for you." -https://faq.soylent.com/hc/en-us/articles/201273045-How-do-I...
"Our goal at Soylent is to engineer nutritionally-complete food products that are optimized for modern consumers' lifestyles and budgets. Above all, we want to make healthy nutrition easily attainable." -https://faq.soylent.com/hc/en-us/articles/203709619-Soylent-...
So by using terms or phrases such as 'complete', 'almost exclusively', and 'staple', and going so far as to remark that it is classified by the FDA as a 'food' and not a 'supplement', Soylent is explicitly marketing their product as a primary or complete food and nutrition source.
Their words. Not mine.