I think you may need to go back to my original post. I am not suggesting that Linux should be the crux of a CS programme. Rather I am criticising the Zimbabwean Universities on the basis of outcomes. The point being, how can a student even emerge from university with said degree and not have such foundational knowledge? Something is wrong here, either in the way candidates are vetted (if your analogy of the pencil is applied) or in the way the programme integrates theory and praxis.
Am I saying a CS degree must teach linux? No, not necessarily. But I am saying a graduate from a CS should know how to use it, just like they should know how to use a pencil.