But if Microsoft really was selling private repo content to OpenAI, it probably wouldn't go through those access controls. It'd be an executive-level decision with enough force to plow through all the red tape, and it'd be implemented as a data pipeline or similar automated process that wouldn't trigger the same kind of notification as, like, a Trust and Safety employee taking manual action.
Probably the better evidence here is in GitHub's ToS where they say in pretty strong/binding terms that they aren't doing this: https://docs.github.com/en/site-policy/github-terms/github-t... . If they are secretly selling your data to OpenAI they haven't left themselves a ton of wiggle room if people ever found out.
(Probably the biggest loophole they could use is to send private repo content to an OpenAI service for scanning/safety purposes. The ToS allows this and they're almost certainly doing it with other services like PhotoDNA. Then OpenAI can just violate whatever agreement they have not to store the data sent to that service.)