This link states that you need PSPlus or XBLive (sold separately) to redeem these codes. Now, while this could just mean if you are playing on PS4 or XB1, you would need one of these, I can't see any mention of PC/Blizzard at all. This coupled with the fact that the dates of release on console and PC are different worries me.
Does this mean that the Sparrow is not available for players on PC? That would be slightly disappointing.