Sorry, no, I never allowed anyone diving under my guidance with just a primary reg attached to an AIR2. The AIR2 is an ADDITIONAL air source, not an ALTERNATE air source.@loosenit2 Air2 use requires primary donate...
With an Air2 you typically use a primary reg with the Air2 attached to the same LP out usually employed for the BCD hose. And then you MUST have another reg, possibly with its autonomous first stage.
So you have your primary, a secondary ready to be donated, and the Air2 which is a third, additional air source, to be used only by you and never donated.
As said, I had never allowed any diver under my responsibility to dive with just a primary and an Air2.
This is a totally unsafe config.
An Air2 can be a good additional safety instead of a normal BCD command, but still requires that the tank is equipped with an independent secondary reg.