He knows the title and the organization of his government is very crude.
But he could not do much with the people he has right now. he had a lot of soldiers. But not every soldiers could become an official
And since he is intending to follow the same method of organization of army as the Orc, he needs people he could trust in high position.
Loyalty is the basis of the power of the Orcs. The same thing that he must employed to the army on his side
In the Empire, he did not need to care that much whether a certain official is loyal to him or not as the landscape of politics there is very complicated and entangled.
Arial himself had entangled most of the nobility and the official benefits with him.
And there is also this teaching of the Three Teachings and the Analects that made scholars had to have just cause to rebel against their own lord.