Powhiri: the sexism edition

Consider this from Voxy:

While Youth MPs were sworn into parliament today, Labour’s Annette King showed outrage over a gender segregated Powhiri.

One hundred and twenty one Youth MPs participated in a traditional Maori Powhiri whereby males spoke from various iwis and were placed in front of females who completed the welcoming call, otherwise known as Karanga.

Labour MP Annette King said she was not comfortable with the "segregated nature" of the welcoming.

And this:

Labour MPs Annette King and Maryan Street have spoken to Speaker after being made to sit behind men at a Parliamentary powhiri yesterday.
— Tina Wickliffe (@TinaWickliffe) July 17, 2013

I think it's wrong to impose a western conception of sexism on Maori protocol. Maori views don't have to conform to western norms. To argue that they should is to impose a particular worldview as the only truth. It stinks of the cultural imperialism of the 19th and 20th century. The rationale behind the arrangements is clear, but those rationales might not have existed for as long as many people assume. Reverand Chris Huriwai explains:

@MorganGodfery I remember being told by Matua Hone Kaa that there were no seating arrangements. You just stood wherever you were and spoke.
— Rev. Chris Huriwai (@RevChrisHuriwai) July 16, 2013

After sounding out others, it appears that powhiri were "organic" occasions. Can anyone else explain further?