Look around long enough and you sometimes see things that might be connected.
The range instrumentation ships used by the US Air Force to monitor missile launches can be used to monitor anyone's launches, not just their own.
Is it possible that the Observation Island or Invincible were somewhere off Japan to watch this launch?
Then again, the Sage might just have been an extra ship needed for a completely obvious need, like a repair and refit for one of the usual T-AGM vessels. Either way, the Sage wasn't responding to Canadian concerns.