Validating legislation - election not vulnerable because of overspending

Some people seem to be suggesting that the imperative for the validating legislation is that the overspending might cast legal doubt over the results of the election. However, it's clear that the election results are immune from challenge based on any overspending. Section 229 of the Electoral Act contains a strong privative clause restricting challenges to the election results (except in circumstances which are no longer available):

s229. Method of questioning election— (1) No election and no return to the House of Representatives shall be questioned except by a petition complaining of an unlawful election or unlawful return (in this Act referred to as an election petition) presented in accordance with this Part of this Act. (2) A petition complaining of no return shall be deemed to be an election petition, and the High Court or the Court of Appeal may make such order thereon as the Court thinks expedient for compelling a return to be made or may allow the petition to be heard as provided with respect to ordinary election petitions. (3) An election petition relating to the return of a member of Parliament representing an electoral district or the failure to present a return at an election for a member of Parliament representing an electoral district shall be presented to the High Court and determined in accordance with sections 230 to 257 of this Act. (4) An election petition relating to the allocation of seats by the Chief Electoral Officer under sections 191 to 193 of this Act may be presented to the Court of Appeal in accordance with sections 258 to 262 of this Act.