How do you know whether or not his apology was genuine? His actions are speaking for him, and his actions firmly say, "I have seen the error of my ways, I will do what I can to rectify the mistakes I've made, and I'm going to do what's morally sound, as opposed to doing what will let me best my brother."
You're letting your first impression get the better of you. Contrary to popular belief, people can actually *gasp* learn from their mistakes and grow as a person!
I know, shocking, right?
He didn't dye his hair blue, either. He dyed it red. Blue is his natural hair color.