MSD's inconsistent application of work-test rationale

In an analysis of the options discussed by MSD over work-testing sole parents, the following table illustrates part-time work expectations for sole parents internationally. New Zealand has chosen the soft option of 5 years along with a soft definition of part-time work (10-20 hours).

I'm with the one year of age option because it deters people from producing children they can't support. But the Ministry argues against the one year of age option saying

"Earlier work availability expectations could reduce the amount of time that parents have available for the care of their children, which could impact on their child’s health and developmental wellbeing."

Yet later in the same Regulatory Impact Statement MSD puts forward this argument to support work-testing the sole parent (who has added a child to her benefit) when that child turns one:

"One year of age is a reasonable period for parental attachment with the child to be established, and is reflected in current parental leave provisions and child development findings."

What can I say? Obviously the Ministry agrees to disagree with the Ministry. However this sort of inconsistency leaves the policy open to challenge from the any number of aggrieved groups or individuals.  The new rules came in on October 15. There are probably people working on a complaint to the Human Rights Commission as I write.