The QR activation looks suspect, however this accident is primarily (or my take, entirely) user error.
Anyone using a kite to reach great heights (big jumps, loops, or soaring in the mountains when snowkiting) must think very hard and make absolutely sure that there will be no accidental disconnection. Two quick options: (1) a solid connection without QR (like in climbing), or (2) a backup connection in case the primary QR connection is released or activates by mistake, or fails (like in paragliding). Yes - more pros and cons follow out of these choices. But those can be considered in advance, and in the end the least risky path can be chosen (obviously including no riding, no jumps, no boots, etc.).
It simply doesn’t do to merely assume that everything will work as it should. That’s relatively OK for foiling and simple riding (my case), where the worst case scenario is basically loss of gear. Which is not a big deal. Losing your gear (well assuming no bystanders etc.) is nothing compared to an accident like this.
You can be reckless many times, and make it. In his words, "it was unlucky, I've pulled many mega-loops, and this never happened". Sure. But the possibility of a fall like this was always there.