I have rejected an update for the following reasons: 10.1: Apps must comply with all terms and conditions explained in the Apple iPhone Human Interface Guidelines and the Apple iPad Human Interface Guidelines 10.1 We found that your app does not comply with the Apple iOS Human Interface Guidelines, as required by the App Store Review Guidelines. Specifically, we noticed your app only supported the top-up variant of the portrait orientation, but not the bottom-up variant. While supporting both variants of both orientations, each with unique launch images, provides the best user experience and is recommended, we understand there are certain applications that must run in the portrait orientation only. In this case, it would be appropriate to support both variants of that orientation in your application, e.g., Home button up and down. Addressing this issue typically requires only a simple and straightforward code modification. However, if you require assistance, the Apple Developer Support Team is available to provide code-level assistance. For more information, please review the Aim to Support All Orientations section of the iOS Human Interface Guidelines. My application can only work in portrait .. I do now?

Did you have any luck proceeding? Sounds like a very weird rejection policy. I always only allow my apps to be standard portrait.