Once is suspicious. This however suggests a pattern of behaviour to hide public records, a deliberate non-compliance with the Public Records Act. And that is a crime. While the penalty is pathetic, he needs to be prosecuted, pour encourager les autres. Failing to do makes a mockery of the law.
But that's not enough. We clearly need law reform here to protect transparency. This must include explicit penalties in the OIA, stronger (and matching) penalties in the Public Records Act, and a tweak to the Electoral Act declaring violation of either to be a corrupt practice - meaning anyone convicted will be automatically removed from parliament. Add a legal principle of absolute ministerial responsibility for the actions of their subordinates, and we would finally have proper incentives for open government.
If Ministers refuse to do this, it is effectively an admission that they are guilty. The question is, how shameless is how political class?