Under the current 'norms' for players giving the opposition a serve when they make an error he has nothing to answer for...it is not a good look but it is not a sin bin or a penalty.
The bigger issue for the league is that there needs to be a shift in policy on how they educate, police and manage players doing that sort of thing as a more general duty of care issue...if Teddy had a neck or spinal injury out of the collision, Arrow could have really made the situation a lot worse by the way he picked him up off the ground and shook him around.
It has been part of the game to some degree for a long time and I'm not averse to that bit of niggle and baiting when a player coughs up the ball or makes an error, it adds a bit of spice to the game....but being a Knights fan and knowing what Alex McKinnon has gone through, it is an area the NRL needs to establish a framework for the players to know when it is not appropriate (e.g. when a player is laying prone on the ground) to go down that road.
On Arrow though, I'm a Blues supporter and he didn't do anything that other players would do from both sides and he did immediately recognise that Teddy was in distress and tried to call help over