A propulsion system that was "inherently safe" wouldn't have dangerous failure modes. Although Virgin has tried in the past to paint their hybrid prolusion sys

A propulsion system that was "inherently safe" wouldn't have dangerous failure modes. Although Virgin has tried in the past to paint their hybrid prolusion system as being "inherently safe", it isn't. No 60klb rocket engine is. To make any such system operate safely and reliably is a big engineering challenge. I think you don't understand the meaning of the term "inherently safe" in an engineering context.