Earlier quoted context omitted.
What worries me is that soylent is 20% based on soy. Some studies indicate that eating a heavily soy based diet leads to increased estrogen levels. Which can have negative side effects regardless of your gender. [0]: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074428/ [1]: http://www.sciencedirect.com/science/article/pii/S0303720711...
There's a lot of misinformation about soy and estrogen levels. This[0] is required reading for soy [0] http://examine.com/faq/is-soy-good-or-bad-for-me/ Ps thanks sol (the owner of examine)
Also the article says things like: "[lowers] LDL and Total Cholesterol" but doesn't dive into the fact that lowering your total cholesterol is bad for your health. Since there is good and bad cholesterols, if you lower everything you're damaging your health (see the 1980s obsession with lowering all cholesterols for example). But, yes, lowering LDL alone is good as far as we know.
I don't think day to day people need to be actively avoiding soy, or heck even not having the occasional soy based meal. But we're talking about a meal replacement diet based almost entirely on soy, that's a big deal, and the health implications cannot just be glossed over.
If anything your link has made more more concerned about the impact of a purely Soylent diet on all groups except postmenopausal women who may benefit.