I kind of find Linus refreshing, although I'm not sure that would survive working directly with him. I think you're begging the question though: surely compatibility/ABI stability/performance trumps extreme security (for some values of 'extreme') for people and in cases where that is true. I happen to agree with you and Linus on this (baring a known exploit of an unpatched security bug), but that heirarchy is nowhere engraven in stone. If I always recompiled a critical codebase, I wouldn't care as much about ABI compatibility. If I'm always targetting a very specific platform, I don't care about compatibility. If I'm sitting on millions of unused cycles in a single-threaded realtime environment, I only care about performance to a certain point. If I'm working on software to control a medical device or nuclear reactor, my priorites around extreme security change.

You're right about that priority for the vast majority of the Linux user-base, but that's a characteristic of those users and developers, not of kernel software in general.