The requisite amount of Pprune accident speculation. The facts appear to be:
1. US registered G IV flown by a known US operator
2. Occurred at LFMQ, LE Castellet, frequent "parking spot" when Nice is full
3. Wreckage is off the far end of runway
4. 3 crew died, RIP.
Beyond that, the BEA will have investigate.
GF