This word not only concerns Satan's dislike for God, but also his disdain for repentance. If he were to repent he would only hate God even more for proving him wrong and having the ability to forgive him. Satan hates that God is his superior and can decide whether or not to forgive him. Satan also hates the way repenting will make him look to the angels in Hell. Satan disdains himself as well because he is not as powerful as God. "Disdain forbids me" shows that disdain and hate are what drive Satan. Satan will not accept orders from God but he will allow disdain to forbid him. The reason for this is that hate has consumed Satan, and by following it he thinks he will gain his revenge on God. This is another reason why he can not repent, because he is full of hate. 

disdain- to consider unworthy of one's regard or notice 2. to refuse scornfully 3. a feeling or attitude of dislike or superiority.