Agreed.
Nobody can work without a visa, and 'work' has a wide interpretation for INZ, including being given your keep in return for helping out.
Here's the detail about WHVs - what you can get depends on which country you're from.
http://www.immigration.govt.nz/migra...orkingholiday/ If he's British and over 30, he could still use the BUNAC IEP visa.
http://www.bunac.org/uk/work-abroad/...-zealand/visas
Either a WHV or BUNAC visa would entitle him to start working on any job he was offered. If he wants a longer term job, he'd need to qualify for an ordinary temporary work visa. The requirements are here.
http://www.immigration.govt.nz/migra.../requirements/ It's not possible to get a temporary work visa without the offer of a job.
If you look up
http://www.immigration.govt.nz/migra...or.htm?level=1 where the nearest INZ office is to where he's going to be staying, you can google "NZ immigration (whichever branch) processing times" to find their current average time for processing a work visa.