Reposting from the thread that inspired this:
pg 109, Channel Life: "Prerequisites champion power (lay on hands)"
pg 106: "Champion powers are available only to paladins, and they can’t be learned by other characters."
Page #43 "Class FeatsThis section specifies the levels at which your character gains class feats, which are special feats that only members of her class can access."
If the person is paladin enough to TAKE feats like Basic Benediction, they are paladin enough to have a champion power. All the archetypes have feats that allow you to pick up class feats so it seems pretty clear that they are considered the class of the multiclass archetype.