good and evil in CF are different concepts from good and evil in the real world.

Neutrals on CF can kill hundreds of orphaned children with zero repercussions whatsoever.

Someone who selected align evil at character creation is an evil character, whom an elf can kill with no questions asked, regardless if that character is sleeping wounded in a pretty flowerbed amongst hugglebunnies and carebears with angel wings growing out of his back.

If you have a red aura, you're evil. If you don't, that elf might (maybe) need a different reason to kill you. Or he might not.

On the other hand, elf assassins aren't around because the imms made them that way. I don't understand why you would object so badly. If you really really want an elf assassin for roleplay purposes, roleplay an elf thief with delusions of grandeur or something. If you really really want an elf assassin for powergaming purposes, tough. (besdies, it would suck). I don't understand why you're fixated on this.