>If you allow a human to edit your code and also give them access to untrusted data (like the Internet), you have a security problem.
Security shouldn't be viewed in absolutes (either you are secure or you aren') but more in degrees.
Llms can be used securely just the same as everything else, nothing is ever perfectly secure
They can be reasoned about from a mathematical perspective yes. An LLM will happily shim out your code to make a test pass. Most people would consider that “unreasonable”.