That's not really a bad thing. First, no beginner is going to be learning about coding OSes so teaching the basics isn't a problem. Secondly, Java OSes are far more common than you'd think, although this was more true of 5 years ago when many phones/smartcards/etc used Java in their OS internals. A lot of the topics in OS concepts would probably be useful if you wanted to hack on OSS Android too. So I don't think there is anything wrong with that book which sounds more like an example and reference book on using Java in OS internals (received mention a shotgun approach).

I don't see any problem with teaching CS concepts in Java. The concepts of message passing or a heap are the same everywhere. I was referring more to the basics of programming where you should either teach at a very low level (pascal is great), or at a very high level (python can work). I think people taught originally in something low level like pascal or C often have the best understanding of memory management and what their instructions are doing.

If I was teaching someone coding, I'd probably start with Pascal (incl inline ASM), then any language based on lambda calculus to get a good understanding of recursion, and then Java in a large team environment so they could understand why encapsulation, delegation and code quality are important. It's a shame more classes don't actually just have all 100 students work together on a single code base - it would be incredibly beneficial. The code would likely be terrible with 100 newbies to Java all hacking in their own required feature to the detriment of everyone else. That would drive the lesson home quick!