People have a right to sue. You cannot bar them from that right on the basis of the fact they were flying the aircraft at the time.
If no other crew have sued over other incidents it is because of their personal choice; the right remains however.
According to the lawyers website, the action is on a no win/no fee basis, so the lawyers are not guaranteed of coming out of this ahead.
QF72 – Singapore to Perth – Information site for Passengers