Some apps need gyro details to determine if the app is being reverse engineered. The idea being if the device is static and not moving then it is been run in a virtual machine and being inspected.
This is probably either a ‘grab whatever you can’ or a panopticlick-like strategy though.
I can see how it would be useful for invalidating data in analytics, seems like a bad choice of partner for an app promoting privacy though.
As an anti-analysis tool it seems like it's more likely to harm users (api is reporting incorrectly, sensor is faulty etc) than slow down reverse engineering much.