Can undead PCs rage?

No one official, but I would say yes. Undead can rage.

Its true that undead who are “the chosen of Neroth” through class or race features (or special PCs) are often depicted as cool to cold in their dispassionate-ness. The soul is the seat of emotions; you have no soul… None the less *anyone* who has visited Canceri and especially Ventaka knows that there are lots and lots (and lots…) of undead that have no trouble, at all, expressing cruel or violent emotions.

Also take a look at the revenant …

If, for some reason, a player was uncomfortable with RPing this I think the fluff surrounding the mechanic of raging could be tweaked into “inhuman/remorseless focus” and “tunnel vision” as your undead seeks to eliminate foes without regard to to the priorities/distractions a mouth breathing (living) creature might entertain.

Is Oozy coming back with anger issues after a long bath in the cold uncaring ocean?

PC Undead can rage

maybe there are some undead who have been around for hundreds of years who have lost touch with so much of their emotions that they have lost the ability to feel hate or love… but that is far beyond PCs area