It’s effectively the precautionary principle, and it’s bad epistemology for the same reason the precautionary principle is bad epistemology.
You’re imagining a danger, which you by definition cannot explain to anyone why the danger is real, and then you’re arguing that some very specific action should not be taken because it might trigger the imaginary danger.
Chesterton is talking about cultural systems which have evolved into their current form over a very long expanse of time. They are the result of a very long dynamic process.
It’s easy to look at the end result of that process and assume that one can easily move things around. But that’s not how the system came to be in the first place.
Maybe the new changes would be inconsequential. Maybe they would even make things run better. Or maybe they would be just an evolutionary dead end, eventually discarded by natural selection.
The point is that one needs to be humble and understand not just the current state of the system but also how it gradually came to be formed over time. Only then should one start proposing changes, carefully.
You’re imagining a danger, which you by definition cannot explain to anyone why the danger is real, and then you’re arguing that some very specific action should not be taken because it might trigger the imaginary danger.