If anything Maedhros just looks even more contemptful of the demon. That smile reminds him too much of someone he'd much rather never think of again.

"It's not about what you deserve, you annoying little cretin. It would be a betrayal of my own self to do something like that"

And he'd be damned if he sunk that low just because of this smirking menace.

"I'm not in the mood to oblige you on that, sorry to say," not really tough. He's not sorry at all about it. "You must have a more exciting afterlife than my people then, Námo wouldn't stand for such a ruckus being made in his Halls."