Why should the Linux foundation be full of FLOSS sticklers? Not even Linus cares that much about freedom, as his refusal to licence Linux under the GPL3 shows
Relicensing Linux as GPLv3, even if actually possible (GPL is incompatible with everything that's not a subset of GPL, including other versions of GPL: GPLv2 is not compatible with GPLv3) would be unacceptable to many commercial players. It wouldn't be end of the world - most big customers, from RedHat to Android folks already have to maintain their own forks anyway - but it would hurt in the long run.