I'd have figured that in a defensive engagement, land-based radars would provide a home-field advantage, so that stealth is not as useful as it would be on the offensive.
It's true that you don't want to be detected by an attacker either, but I believe that doesn't matter as much, since in an aerial engagement, the first one detected is the first one dead anyway.
So stealth is good, but not, like, as good over Canadian territory, as long as we're being supported by good detection.