It's interesting...funny, really. There are those who absolutely believe (because they've been told?) that leaving a helicopter running without a pilot in the seat is...DANGEROUS!
It is not.
On a solid surface, with the rotor/engine at idle, and with the controls suitably immobilized, a turbine helicopter will happily run all day long until it runs out of fuel. The collective will not "jump up" to full travel. The ship will not spontaneously explode or roll over. Random gusts of wind will not upset it and cause it to destroy itself. Nothing happens. Nothing will happen.
Let me repeat: I have never, ever, EVER been in a helicopter on the ground, at idle when a "gust of wind" caused the rotor to do something...anything...that required a control input from me. With the cyclic stationary, if the rotor flaps it will be brought back to level. That's how the linkage works. I have never, ever, ever had a helicopter roll over while I was in it at idle. And in any event, the cyclic has limited effectiveness with the rotor at idle. If your aircraft begins to roll over while you're sitting there at idle, there is nothing you can do- it's going over. You cannot *snap* the throttle open fast enough. Just ask those New York Airways pilots on the roof of the Pan Am Building what they did when they did when their S-61 rolled over on them.
A pilot in the seat with the rotor turning CANNOT see anyone approaching from the rear, especially the rear quadrant on the opposite side of that which he is sitting. A pilot in the seat CANNOT physically do anything to prevent anyone from approaching the helicopter from any quadrant. He can shout, and even gesture wildly, but there is really nothing he can do.
Leaving a helicopter idling without anyone in the pilot's seat is not "inherently dangerous" or hazardous or risky...IF DONE PROPERLY.
Unfortunately, the FAA is in a quandary here. As already reported, their own definition of pilot flight time is "skids-off to skids-on." So they cannot really say we *must* stay in the seat with the rotors turning. Because if they did we'd say, "Why? Because we are acting as PIC with the rotors turning, hmm? And so then we can log PIC time, hmm?" I assure you they do not want to open that can o'worms.
I say now the same thing as I said before: Let's wait and see what the pilot did or did not do when he got out. Did he do everything "properly"...i.e. did he reduce the power to idle and secure the controls, and was he on solid ground? Because if he actually did all those things, the Astar "shouldn't" have rolled over. So let's wait and see. We'll know soon enough.