The relation is simple. When you are a good deep free diver and can go down to 20-25 meters on a single breath, you are mentally quite sure of being able to perform a CESA from the same depth.
Your mental state is of utmost importance when you suddenly are OOA. If you are calm and act properly it is easy to reach the surface with no harm. If you panic, the chances are much lower.
As modern training to free diving is focused on brain and body control, a good deep free diver is almost impossible to panic when scuba diving and being OOA...
So I repeat my suggestion to the OP: if you are afraid of a CESA from 30m, get trained to free dive at the same depth. It will take several months and a lot of effort, working both on your body and particularly on your brains, but at the end you will not be anxious anymore of being OOA at 30m.
In the meanwhile (and even later) a small pony tank is a good reassuring thing to always carry with you.
If others cricticise you for that, leave them talking.