MSDS sheets are about the safety of the people using the product, they don't generally provide commentary on environmental impact. The MSDS for vermiculite, by the way, says you shouldn't breathe it or get it in your eyes because if you do either of those things it will cause irritation. Basically the same kinds of cautions one would be well advised to follow with any sort of dirt/clay/mineral/sand/etc.
The fact that a particular substance has an MSDS doesn't automatically mean it's dangerous. The MSDS might say that there are no hazardous ingredients and no special precautions for handling or use. And even if it is hazardous to breathe, for example, that doesn't automatically mean it has to go in a landfill.
Vermiculite is a special type of clay that is (among other uses) commonly recommended for soil conditioning--it is mixed with soil that is unsuitable or inhospitable to cultivation to improve its characteristics. So there's absolutely no problem with disposing of it outside of a landfill. In fact, in many areas, you're actually improving the soil by doing so.