I would argue that putting a hard deck rule in place has the ability to
create a safety issue rather than mitigate it.

What happens when the competitor drops below the proposed hard deck?

Must they simply land?

Do they give up trying, and then land out trying to get home, possibly
unfocussed and a bit dejected?

You would then be putting pilots in a situation where they are forced into
landing in an unknown environment and by doing so increasing the risk.

Statistics are statistics and can be manipulated to give the desired
outcome.

The issue here is field section, or lack thereof.

There are many factors that influence what is a safe height to climb away:

1) Experience
2) Hours on type
3) Terrain
4) Having a chosen / planned land out option
5) Aircraft type
6) Weather - reliable day Vs unreliable day

Competition gliding is in decline, keep adding rules which removes the
pilot judgment, the decline will be more rapid.

Just my humble opinion.

1000 + hours
Flown 15+ contests
Past contest director
150 hours in the mountains.