I feel like he would only want to be healed if his Empress wants it. He wanted to step down bc he knew he couldn't stay by her side with his scars, but Lass wasn't having it. That's why she gave him the muzzle. Now, he's able to stay by her side as her right hand. He wouldn't have been and even the Emperor didn't want him, but Lass made a deal with him to cover the scars so that Sing could stay with her. Aaaand that made him unconsciously jealous, but he gave him and allowed Sing to stay. So he pretty much is useful to her as if he never had the scars.
Yes, I agree with you. *claps* Sing is very handsome. He is easily my favorite character out of the whole series. So much so I want some side stories of him and his background and then his future after the end of the story. I wanted the bitch dead who ordered him to receive the "Glasgow Smile", but he's still beautiful. I would love to see his face Scarlets again too, but I have to admit....I freaking love his muzzle.
I LOVE YOU SM SING AUGHHAVSJAB LASS TELL THE EMPEROR TO HEAL HIS SCARS I BEG