And even if these cruise missiles were completely undetectable, it would still fail unless the strike takes out 100% of the enemy nukes. If even one is able to survive, you risk a nuclear holocaust.
Being able to theoretically wipe our all the enemy nukes without using any of your own is strategically nice to have, but on its own it isn’t enough to negate the threat of a nuclear exchange. At best, it should make your enemy more reluctant to retaliate with a nuclear launch, assuming they realize that they aren’t getting nuked and that a launch would potentially change that.