Yes.
The Sportsnet app does allow you to stream your Sportsnet+ live streams via AirPlay.
You must however use the Airplay controls within the video player, and not using Screen mirroring enabled from the iOS Command Center.
Instructions:
- Open the Sportsnet+ section of the app and initiate playback of a live stream
- Tap on the AirPlay icon on the row of player controls (if you do not initially see the AirPlay icon try to lock and unlock your screen to see if the icon appears after the unlock)
- Select the Apple TV device you would like to AirPlay to
- The Airplay icon will turn blue once a successful AirPlay playback session has started