I think they were trying to say that you shouldn't try to commit work that is not yours to give away. There's another section down below about it, but the bullet point up top became confusing.

This point is obvious to devs with more experience but has been a real problem with some junior devs at some of my companies: They see something cool the company is doing in an internal project and think it would make a great contribution to some open source project, without thinking about the problems with using their knowledge of closed-source code to submit substantially similar code (or in some cases, copy and pasting) to an open source project.