Redemption is a religious concept! It is absolutely about morals.
The only person that can redeem Illidan, is Illidan. I've already explained how, and it absolutely requires him to change who he is.illidan can be redeemed by the people of azeroth without changing himself. all he needs to do is prove himself.
For another example, this one from in-game: the satyr in Ashenvale that seeks redemption, Avrus Illwhisper. He had to abandon his satyr brethren and willingly sacrifice his own life to save a night elf child, something he absolutely would not have done before seeking redemption, in order to be redeemed. He had to change.