It was reckless not intentional and merited a red card. You have to be an idiot not to know that there was a chance of kicking someone and hopefully it gives players inclined to be this reckless second thoughts about taking those kind of actions.
The commentators missed it but Owens (ref) clearly called 'still advantage' just before he chipped. He knew that it was a shot to nothing. A contrast to the boringly unambitious gits who attempt a drop goal when there's a penalty advantage in front of the posts.
I think that you're right about Van Niekerk. Haymans went in for a big tackle and it probably would have ended safely if Van Niekerk hadn't pulled him down. That's looking at it from Hayman's point of view though. From the point of view of rugby this was a dangerous moment that could easily have resulted in serious injury. As a father of a boy who's getting interested in rugby and a former player myself I don't want to see that kind of incident on a pitch regardless of the intention of the tackler. As a tackler you have to take responsibility for the conclusion of a tackle the moment you lift a player in the air and remove their control from the equation. IMO it doesn't matter that you didn't anticipate somebody else intervening. So while I don't think that there was any malice involved I do think that a red card is an appropriate response to this kind of incident.