I would agree with most of what the good Doctor said however, given the size of a CPR mask; I would keep it. It is true CPR does little, if any good without being followed up by ALS and hospital care.

But in the case of hypoxia, (a lack of O2) Positive Presser Ventilation (PPV) by way of a one-way barrier mask is just what they need.

As for metabolic acidosis which is a state in which, the blood pH is low (under 7.35) due to increased production of H+.
It is true it won't help but that is comparing apples to oranges isn't it.

As for Exsanguinations it is a dramatic cause of death in humans. It might be more precise to say that exsanguination is a mode of death rather than a cause. This is again the apples to oranges deal.

A very good case for CPR is lightning strike or cold water drowning; in both cases the heart wants to start again it just needs a little help.
So to wrap up I'd keep the CPR mask given its size and weight and make sure you get CPR training and as the good doctor said, “join a Vol. Fire and Rescue Service”.

Sorry to disagree with you Doc.

PS
Oh and in the case of Exsanguination (bleeding out) a tourniquet may be just what you need to prevent Volume shock.