Currently, some AppleTV channel apps (like CTVNewsGo), require a login to OptikTV in order to watch the content. This means that, even as a subscriber to the channel through PikTV and able to watch live content, some shows (like the news) are not available to watch if not live. As a subscriber, whether PikTV or OptikTV, it would make sense that I should be able to get access through the AppleTV apps. I can (for instance) stream episodes of the news on my iPhone and AirPlay it without logging in to anything (but the quality is not the same and its not as convenient), so it's weird that it's a licensing issue to do that on the AppleTV app.
Other iPhone apps (like Discovery Channel) will similarly not allow sign-in to watch their content, even though I subscribe to those channels through PikTV. Feedback to the apps goes unanswered of course.
The other option is to make shows like the news available to watch at any time like other episodes of other shows are.