In Robbo's defence, I didn't think he intentionally targeted Dangerfield, it appeared to me that Dangerfield suddenly came into Robbo's path and then he cannoned into him.The fine seems about right. You don't want people just taking other players out like that all the time, free kick will often be missed too as it is in play but off the ball. if there is no penalty there, then it just invites the good old fashioned fix up off the ball at a center bounce.
$3500 seems steep, got to deter it though, there is wip lash, back injury, kidney stuff all possible happening there and lets face it, it's going to be the best players targeted with this sort of hit. I'd prefer it not happening to Zorks and beams if possible,