Is it considered just for one to rule by other than what Allah has revealed, even if he does not oppress the people?

The Muslim nation is one nation, therefore, Islam has made it obligatory to appoint a ruler who governs Muslims according to the Book of Allah and the Sunnah of His Messenger, establishes justice and the hudud (prescribed punishments), spreads Islam, and protects the nation. The ruler is responsible for his subjects, and obedience to him is obligatory as long as he rules by what Allah has revealed. If he rules by other than what Allah has revealed or commands disobedience, then there is no listening or obedience. The ruler is entrusted with the nation, and he must be gentle with it and advise it. If he does not do so, it is obligatory to advise him, and if he does not respond, the Muslims choose another ruler. The just ruler has a great virtue and a noble status on the Day of Resurrection, while the unjust ruler's recompense is the torment of the Fire. Speaking the word of truth is an obligation upon every Muslim, and the greatest jihad is a word of truth spoken before a tyrannical ruler.