Kevin Gu started working on the AI in 2019, it was first broken sometime in 2018. It’s in the patch notes history. If you read his posts here:
You can see he was working on reverting changes that were made prior to his tenure. This is all in the patch notes somewhere. I honestly can’t be bothered looking for it, take my word on it or not. He wasn’t to blame for the major issues and doesn’t deserve ridicule regardless. The joke about the “biology major” was always redundant.