What it means is that we lack the ability to prove either of those theories, not necessarily that either theory is bad.
Saying COVID evolved from nature is sort of a catch all. It's like saying all possible theories in aggregate except for the lab leak theory.
For example: What are the chances of anyone but you winning the lottery? Quite high.
So when they say low confidence of the lab leak theory it most likely means it's a crap theory.
Low confidence means inability to prove or disprove. That is it.
Edit: extrapolating further about this is just a Rorschach test.
I have a low bar for crap theory. As long as it doesn't have evidence that confidently supports it, it's crap.
The other guy has a high bar for crap theory. A theory without any evidence, to him, is not crap.
It's like arguing over what temperature is hot and what temperature is cold. Pointless. An Eskimo has a different definition of cold and hot then say some guy who lives in a desert. Put them in the same place and let them debate about whether the current temp is hot or cold... That argument ends up being an argument about vocabulary. What is the definition of hot or cold?
Who fucking cares? That is my point.