Yes, agreed that big business can now circumvent pia by pulling such a stunt.
This will only change if the target, in this case, economic damage, is changed.
I'm sure this will probably occur, however, it would be ironic for big business to want this. I mean a central umpire to rule over negotiations to see if it was "fair". Ultimately, this does of course take away control from the participants but you'd have to think that most businesses would want a negotiated outcome because they retain some form of control over the final result, As opposed to none.
I think Qantas may have thought their demonstration of powers could have some how knobbled the fair work act. On the contrary, I think it will enhance it over time by enabling fair work australia to referee in such disputes, without such a harsh indicator (economic damage) to be the trigger, for the umpire to come in, as originally intended.