Do I understand this correctly: somebody at MSFT thought it would be a good idea to provide internal LLM with unfettered access to ALL of the GitHub code? “Just like SQL has”?

The difference is that (A) SQL is deterministic and (B) SQL implements internal access control (and how well that works).

Prompts from non-authenticated user should have no access to any private repositories. The real question is: can you trust MSFT GitHub with your code, now that “outsourced” engineers are supporting it?