Actually, if you only read the license files included with the kernel source, you'll be very confused and unsure of what you can actually do. The GPL is painful

Actually, if you only read the license files included with the kernel source, you'll be very confused and unsure of what you can actually do. The GPL is painfully vague, and there have been endless debates about how it applies to kernel modules, programs, etc. (such as this very one we're having now). (And I'm taking into account the clarification files in the source). Linus' LKML clarifications are post-hoc and not linked in the kernel files anywhere. I do agree with you that the GPL_ONLY "code is law" theory has some merit - and certainly a judge could use that as part of a ruling to uphold that interpretation. But I don't think that this aspect of the kernel license is going to be tested in court any time soon, so it's all speculation at this point.