Did the rep say which reg he didn't like, or does he not like both of them? When he says use the same as what's on the cal gases, he doesn't mean coming off the cylinder with those does he? I hope not!
The small one you see in his picture with the gauge on it is NOT a regulator. There isn't a diaphragm. That is just to regulate flow. I use those on my paint spray guns.
My zero air bottle has a big regulator on it like he has and then the other end of the clear hose has a small low pressure regulator at the BAR97 machine where the zero air goes in. It is the same regulator that goes onto the small zero air bottles with a compression fitting.
Good judgement comes from experience. And experience? Well that comes from poor judgement.