Well of all the testing they did, apparently none of the people doing it rode a roller coaster. At least not a properly wild one.
Roller coasters have limited G force - in order to maintain consciousness at 9g fighter pilots need to be in tip top shape and wear a pressurized suit to keep the blood from pooling in your extremities. So they can probably assume roller coasters don't go above 5g, and increase the limit for what triggers the "crash" reporting.
Or maybe a bit of 'AI' can tell "this looks like I'm on a roller coaster" and disable the crash reporting for a few minutes.
What I wonder is how they tell the difference between "I was just in a crash" and "I just dropped my phone on the floor". Obviously they have that sorted or false alarms on roller coasters would be the least of their problems, so I'm sure there's a software solution at hand for roller coasters that won't involve anything crazy like geofencing amusement parks.