If you remember Flipboard, Evan Doll was in the iOS team and also taught the CS183 at Stanford. As per his LinkedIn as soon as he left, the same month he cofounded Flipboard although the app was released 1 year later.

I have a few coworkers from my team that cofounded companies and they too have 1-2 month gap after they quit and they all got funding :)

It was around 2011.

I don’t think the policy changed as per se. It’s just they found proof of him trying to hire a part time help.

I had a co-worker around 2013 ish who just wanted to blog and put personal projects code to GitHub. It was not recommended and needed VP permission … basically a hassle.