Chevy couldn’t really figure out what happened, according to Automobile (emphasis mine):

Chevy engineers were unable to find a solution or offer a definitive explanation for the calls, but it seems reasonable to conclude that a particular combination of speed, g load, yaw angle, and longitudinal and lateral acceleration/deceleration rates can trick the system into believing the vehicle has been in a crash—or that its driver is auditioning for a seat with the factory-backed Corvette Racing team. Even more odd, Chevy insisted to us that it in all its miles of ZR1 track testing, it has only heard of this scenario when Pilgrim is the driver behind the wheel, and only when he’s flogging the car at the NCM track.


Pilgrim, this ZR1, and NCM are apparently just cursed, though cars registering enough G forces to trigger Onstar’s crash alert system has happened before, notably in modified Cadillac CTS-Vs.

I emailed GM to see if they could shed any more light on the situation and will update this post if I hear back.