I think the excuse of 'he just has a poor tackling technique' goes out the window in professional sport. His job that he's paid for is to have good technique, so if he's so incapable of doing that then he shouldn't be allowed to play, because he's a danger for other players. Hernandez didn't drop or change direction at the last second so there's really no mitigating factor here.
If World Rugby wasn't such a joke they'd ban Ngwenye for dangerous play. This isn't just an unfortunate, unavoidable accident - it's him being completely incapable of doing the basics. And if that means he's a danger for others, he shouldn't be allowed play until he learns not to be a danger.
Does anyone know what 'liable to sanction' means for feigning injury? If it means they're liable to be penalised then it's not much of a deterrent. I would have preferred to see 'liable to a yellow or red card and suspension'.