I think they need to be more realistic on mitigating circumstances for this sort of stuff though, Swinton one fair Ofa's one, the wallaby clearly dipped into the tackle, not a tremendous amount but enough for it to go from being a safe and reasonable tackle to make to one that saw him sent from the field. At normal pace there's essentially zero he can do to alter his tackle
A small dip has to be assumed. Players lower body height into contact. A tackler can't assume that a ball carrier isn't going to get a little lower when they brace for contact vs running freely.
The mitigating circumstance of a sudden drop before contact is really around a player slipping so that they are way lower in contact than they otherwise might have been.