Linus is saying that programs that use the Linux kernel HEADERS need to be under the GPL or LGPL. If you're using system calls(and associated headers), you're

Linus is saying that programs that use the Linux kernel HEADERS need to be under the GPL or LGPL. If you're using system calls(and associated headers), you're fine with any license, but using kernel headers to directly access kernel calls in non-GPL code is not allowed. Most non-GPL userspace programs use glibc, which is LGPL(and therefore can be linked by any license). If Google copied the headers verbatim, then created a non-GPL licensed wrapper around those headers, that is a GPL violation.