Possibly wrong but I was under the impression that once the ball has bounced, Which I think it did in this case... then the tackle in the air rule isn't applied?

I guess you have to draw the line somewhere or players could jump when receiving a pass so as to avoid getting tackled.
I'd still put some onus on the players to be careful with their actions and penalise them if they're reckless.

I suppose a penalty could still be given if an attacker is put into a dangerous position by the defender just like in any other tackle. It just isn't an automatic penalty.

In the NRL the anomaly is that you can tackle an attacking player in the air, but not a defender. So under the same high ball if a full back catches it in the air and is touched its a penalty, but if the attacking winger does the same its not.

Robbo is right, it is illegal to tackle a player in mid-air attempting to catch a kicked ball on the full. If the ball bounces first the player is fair game.

More difficult to hit the jumper with the same momentum following a bounce I'd say, given that there's less time available to pinpoint where the ball's going and react accordingly. But worst case I'd have to agree: both could be equally serious.

As long as it stays outside the remit of the VR I agree with this. And yes, even as a Leeds fan I thought Mathers' offence warranted another shot at goal and possibly a dismissal.