The Newberry Caldera has a history of exhaustive eruptions, which is why there is no cone. Every time it erupts, the magma chamber exhausts itself, empties, and the resulting cone collapses into the magma chamber. Its eruptions have been the largest and most spectacular in central Oregon. But it's been several thousand years since the last eruption. It's sleeping -- for now.
It's an interesting experiment they're proposing, and it's probably safe. That area of central Oregon hasn't had an eruption in a very long time.