Remember when Xykon killed a bunch of self-righteous Paladins...

[Metastachydium]

The good lich variant in Libris Mortis even says it is "conceptionally an oxymoron." In other words, it acknowledges that the basic concept of a lich includes "evil" as a defining trait of lichdom.

Also, I can't quite see how these variant liches are relevant to the discussion at hand, since, again, SoD clearly establishes (twice, in fact) that

Spoiler: SoD, p. 60

Show

„[s]uch a path (…) lead[s] to an irreedemable state of utter depravity”

as far as Xykon is concerned.

(Aand finally, there's a new Orc in the Playground.)