"Minding their own business" isn't a problem, refusing to participate in a Non-Optional briefing IS.
like it or not, it's Air NZs plane and their procedure is the ooax must listen to, agree with and show understanding of the exit row requirements. I'm not sure where you're from but it's not just a "are you ok to help us" by rote- it's an actual.interactive briefing with responses required on most carriers D&G...
The other thing you're not seeing is it doesn't matter if there's other pax in that row- every pax must be briefed as though they will be the only one left standing in the worst case. Best case they'll all help each other but that's not as likely given statistics. Half of them may be dead in a serious accident.
again, sitting in the exit isn't the same as being responsible for it. Take it from those of us who do this for a living 😉
and fyi, I am never anything but polite when delivering a briefing and requesting their undivided attention while I do so. I'll smile, but I'll wait as long as it takes for them to put down the phone rather than half ass an important safety briefing