You can use a local model, which will go down exactly as often as gcc will. We may still have hopeful notions of being able to understand the codebase, but the reality seems to be that the codebases we don't understand will be the ones that will win out in the market, because they'll be cheaper while still only having about as many bugs as they had when people wrote them.
Because you're better able to take over the codebase a local model wrote than one Claude wrote? The original question was about taking over an LLM-written codebase, it doesn't sound to me like the argument was about a codebase that Claude, specifically, wrote.
What does it matter what the codebase is made with? If Claude is down, use Codex, or Gemini, or Deepseek. That version of the argument is just way too easy to counter.