His opponent was, I believe, Antonino Rocca, who was a very talented wrestler, so I would imagine the powerbomb was meant to go like that.
The original "botched piledriver" version looked more like a Ganso Bomb in so much as the receiver's head slipped out of the aggressor's thighs and he just dropped him. From there, as with most moves-that-started-as-botches, it became more refined and eventually what we see today.