You realize that the word narcissism is not fully encompassing of all aspects of the character in the tale that inspired the word though right?

The word describes self-centeredness on the shallow end and on the deep has a diagnostic aspect for a mental disorder that has nothing to do with sexuallity. Referring to asexual people as narcissistic for not being sexually attracted to people would be considered quite insulting. Look up the dictionary definition or the DSM for the disorder and show me where it mentions asexuality if you can.