The Imperial Guards of the Duke were the cream of the five hundred billion Centaurians.
Each of them had to go through dozens of screenings, spent decades serving in the regular army, finishing tough missions, and even then, had to fight against a hundred people for their spot.
It'd be an understatement to say that they're geniuses. Every single imperial guard was elite of the elite.
Even the weakest of them was a rank 1. There were even several peak rank 2s.
There were a few rank 3s as well. Not too many, but each one was an out-and-out genius.
Even if all the Provinces under Centaurus rebelled, the Imperial Guards headed by twelve rank 3s were enough to crush them. Such a force naturally had its own pride and dignity.
Even if it's the guest of Duke Cassius, Imperial Guard refused to be insulted.