However it's the consistency that would make it meaningless, since alignment either results from actions, intent, or behavior, a Lich has no connection with any of the lower planes, ergo it has no metaphysical link to evil. And even if and that's a big if there was, it would still make alignment meaningless.
It doesn't matter if it's a human philosophy or not, certain acts (and thoughts) are good, if the character has them they are moving towards Good, there is no way to be always doing good things and thinking Good and not be so in alignment that I am aware of.