Warlord's Bloodlust not healing Karthus' Q (is this intended?)

Karthus' Q counts as a critical strike. Not just because of the change in the numbers being displayed with the little symbol, but Riot has said that Randuin's Omen reduces critical strike damage and that magic abilities that can crit: Anivia's E, Soraka's Q and Karthus Q are counted as criticals towards Randuin's Omen. Why isn't Warlord's Bloodlust healing Karthus when he lands a critical strike then? I'm not putting this in the 'Report a Bug' forums because I honestly am not sure if this is a bug or an oversight.