Well, canonically, Norris ends up being the hero of 5th FW. That may or may not change with Mongoose's rendition.
In canon, Norris deposes Santanocheev [who really is an idiot anyway] and the Imperial Navy defeats the Zhodani in two key theaters, Efate and Rhylenor. The War ends with an Imperial victory inasmuch as the Imperium gains a few worlds and secures its borders. The key victory is the destruction in detail of much of the Zhodani, Sword Worlds and Vargr 40th Squadron fleets. And the fangs of the Sword Worlds yanked out with extreme prejudice as well, thereby securing the Darrian Confederation's frontiers as well.
I should note that Norris is never portrayed as a fleet commander. He is strictly a political figure, but was trained as a Naval Intelligence analyst. His role was twofold: keeping the sector nobility off the backs of working admirals and he assisted with operational planning. He never took the field himself, and he didn't interfere with the actual command workings of the Navy.
But that doesn't mean that some of the means to his ends weren't on the howling screaming edge of what is allowable for a noble to do. If his gambit had failed, he would have been made the scapegoat for the whole episode.
But that is the kind of emergency risk taking that the Emperor wants his nobles to do... identify what's best for the Imperium as a whole, marshal the assets to do the job, and provide leadership to get the job done.