A viable six inch tall being appears to be an extreme example of dwarfism, even among the group of reportedly diminutive ETs. If, as seems likely, they can control their own genetics, such dwarfism appears conceivable. The reason for wishing the existence of such a small being is unclear. Perhaps it was intended to live in an unusual environment, where its small size was necessary, or at least offered notable advantages.
One wonders what happened to this being, and how its body came into the hands of the scientists.
Extremely small indeed, however the San Pedro Mountains Mummy was purported to be a mere 14 inches standing, Lucia Zarate reached a grand height of 20 inches at the age of 17.
Extreme, but within the realm of Microcephalic osteodysplastic primordial dwarfism - perhaps.
However, the name Greer is a giant red flag. Big enough to cover the entire globe I would say.