The comment above has to do with package signing, which is a security feature. It prevents malicious software from replacing legitimate programs on your device (e.g. a malicious "messages" app cannot overwrite the legit "messages" app you installed). It doesn't have anything to do with DRM.
That's all the μG team is asking for: If you already have write access to the entire system, at least provide a simple API to circumvent the signatures.