It kills insects and microorganisms (just like it kills almost anything else). So the net effect would be preservative, and it's still used as such in a few obscure contexts despite its toxicity—the American FDA allows very small quantities as a preservative in eye makeup, for instance.
Given the mess on the floor of that one room, there may have been a considerable amount of cinnabar (mercury sulfide) pigment present. And liquid mercury was widely used in Chinese alchemy. Plenty of possibly routes for contact, either accidental or intentional.
Not unless free transport, and free accommodations for those who have to travel for more than a couple of hours in each direction, are also provided. The government could stock abortion pills at more remote clinics—I mean, unless there's some unusual shelf-stability issue I don't know about. They just don't.