[adrusi]

I doubt that Apple's primary concern is people breaking their screens. It would actually be quite difficult to break your screen by putting heavy weights onto a spoon.

No, Apple's concern is supporting this app to the future. They don't know if they'll be sticking with this same kind of sensor for future models, and they don't know that any future sensor will be backwards compatible for this app. If people get used to using this app, suddenly they'd be under an obligation to keep it working, thus losing options for future designs.

[fpgeek]

Considering how frequently and heavily Apple pushes developers for other updates (e.g. new iOS version support, 64-bit support, etc.) I'd be shocked if future support were any consideration in the rejection. I'd expect Apple to be perfectly happy to deprecate and/or replace an API, allow changes in undefined behavior in future models and so on. If the app breaks, so be it.