The article the OP linked to doesn't particularly bother me. The netball tournament is specifically for Muslim women. They are putting in place rules (presumably) appropriate within their culture values. Under those values it pushes the boundary of decency for men to be watching women compete in netball uniforms. The concerned dad could let his daughter join a regular netball club and watch her every Saturday.
Dads never went backstage at my daughters ballet recitals. That too was about decency, albeit with a different threshold.
The Human Rights Act allows clubs to engage in what would otherwise be unlawful discrimination (sex, age, ethnicity, religion, political beliefs, sexuality, disability etc). It would be perfectly legal to have male only gyms.
There is also an exemption that allows for sex-specific public facilities in the interest of 'decency'. That's really designed for bathrooms etc but you might interpret it to mean you can have a female only session at a public pool.
If we can reasonably meet people's cultural needs they will feel recognised and able to participate in society. They are much less likely to feel marginalised and therefore drawn to any form of extremism. Being a kiwi tends to mellow out cultural values within a generation or two.