I doubt that he is scared of Linux ... after all ... these OS wars are largely religious.
My own experience with Linux has mirrored Ken Thompson's (see attached link) ... some of it is written well, much of it isn't. BSD varients have worked much better imho and I'm looking forward to see what OS X is 6 months from now.
check out this link for comments by one of the Gods of the computer world (and a much better designer than Linus)
"Computer: In a sense, Linux is following in this tradition. Any thoughts on this phenomenon?
Thompson: I view Linux as something that's not Microsofta backlash against Microsoft, no more and no less. I don't think it will be very successful in the long run. I've looked at the source and there are pieces that are good and pieces that are not. A whole bunch of random people have contributed to this source, and the quality varies drastically.
My experience and some of my friends' experience is that Linux is quite unreliable. Microsoft is really unreliable but Linux is worse. In a non-PC environment, it just won't hold up. If you're using it on a single box, that's one thing. But if you want to use Linux in firewalls, gateways, embedded systems, and so on, it has a long way to go."
I use Linux, OpenBSD and OS X. I love them all. They all have their good points and their bad. This business of starting a OS war is stupid. I didn't think that Linus would stup to such levels. Oh well.
You have to realise ...
1. Linus is NOT talking about MacOS X. He is talking about the Mach microkernel
2. Linus is known to be highly opinionated about microkernels in general
3. Linus is known to be highly critical about other Unixes in general - especially those that are not open source and built using a Linux-like model (i.e. pretty much ALL of them!). Why else would he build his own from scratch anyway!
Having taken all that into consideration, you also have to realise that Linus' quote was taken completely out of context. Read the book (or excerpts of it to find out more)
I know that he said that the Mach Kernel is crap but it still *bad*...
Just because someone did something good with it, it doesnt mean that he can bash it.
There is a saying in greek which goes like this:
"Osa den ftanei i alepou ta kanei kremastaria" (from one of aesops myths)
meaning (rough translation) When one cant attain something he passes it off as bad.
Obviously Linus did not want to use the Mach, fine, let others use it.
Furthermore there is no need to be bitter about such a topic. I was reading an e-mail conversation between him and tanenbaum (creator of minix). It is just SO mindblowing! I get the impression that he has the "my way or the highway" mentality..... I detest people like that!