Right on. Most CS students are unaware that they have signed on for math, set theory, relational algebra, etc. They mostly think that they're going to learn how to program games and become rich.
There's also the other subset of CS students who are forced to take beginning CS classes due to their major. Bioinformatics for instance. They really don't have the head to figure this stuff out.
I would say that 95% of the CS students I have taught in lab or tutoring were in above their heads and 60% either switched majors or failed. Some of them failed the CS intro to programming 3-4 times before they figured it out.
You may not realize it, but the 90/9/1 principle applies to CS as well. 90% won't get it, 9% will get through it, and 1% will go on to Masters or PhD.
So, the best way to teach CS students about Linux is to wrap it up in a series of lectures that include different OSes such as Windows, Linux, Mac OS, DOS, etc. That's probably the only way to get them interested (most will gravitate towards the pretty ones).