iOS Enterprise App not from AppStore – any warranty issues? We distribute a non-AppStore-app to our agents in the field. Since our app is not from the App Store, it has not been reviewed by Apple.  An Apple retail store worker in Australia told one of our agents that the app is not authorized, and to stop using it or else they will void the warranty.

Can anyone verify that the Apple device warranty is not affected at all by non App Store apps? The device isn't even jail-broken and nothing in the warranty clause talks about faulty software (that I could find). I am also certain the Apple (or retailer) employee is wrong because apps cannot break the system!
You can't void the warranty by using non-App Store apps.  The warranty covers the hardware of the device, not the OS.

Thousands, or hundreds-of-thousands, of corporate and school users develop and use apps that are not vetted through the Apple App store.  In fact, Apple encourages this type of activity.  Their own site for enterprise development states: 


  The Apple Developer Enterprise Program allows you to develop proprietary, in-house iOS, and watchOS apps that you can distribute to your users in your organization and outside the store.


What you're told by the Apple retail employee is completely wrong.