I don't think it could have worked anyway, given https://trufflesecurity.com/blog/anyone-can-access-deleted-a... . The best they could do is hide new test material, and then only if the private repo is kept distinct and isn't recognized by GitHub as a fork.

The most recent comment from the CEO is well written and reasoned, worth the read (for other HNers reading this)

I'm not sure I buy the "joke" part, I read that as part of the walking back