Unless you present a specific reason to think that Soylent is unsafe, you're just blowing hot air.
The reason I even bother pointing this out is because you seem like the kind of person who might actually be able to present a specific reason.
Obviously, it's not safe to assume that it can replace all food, period, but I don't see/haven't heard any specific reason to suspect that it would be dangerous to consume it in large portions on a regular basis.