Soylent sounds like it's made of soy, but the name essentially means cannibalism. I'd expect the former to kill enthusiasm from the energy drink market (where the cannibalism angle makes it sound more extreme) and the latter to put off everyone else.
The literary evocation is far more powerful than the word-part "soy". Even so, given soy's ubiquity I suspect that no one would seriously be turned off by it at this point. The name doesn't "essentially mean cannibalism", it refers to a fictional future company that makes the bulk of the worlds' food in the form of Soylent Red and Soylent Yellow. In the movie Soylent introduced a new product Green that you refer to, which means that the only people who are disturbed by the name are those who take things too seriously and also didn't actually watch the movie.
I haven't seen Soylent Green in a long time and all I remember is "Soylent Green is people". I'd guess that many people who haven't seen the movie know that line and nothing else.
