Earlier quoted context omitted.
It's not just employees, it's students. My dissertation project is in a Github private repository, yet it looks like I abandoned Github - at least to the few people who seem interested in what I do. Combine this with the use of StackOverflow Careers and Github Jobs, I might as well have died as far as potential employers are concerned.
What's the motivation for making your dissertation a private repo?
It was advised in my first year by a few tutors to just keep it in a private repo until hand-in. I'm fine with that, in fact, just publically listed a dodgy encryption algorithm I wrote for a class!