I don't think any sane reading of the GPL would imply that it "taints" a host platform (via its libraries), whereas the inverse, non-GPL code linking against GP

I don't think any sane reading of the GPL would imply that it "taints" a host platform (via its libraries), whereas the inverse, non-GPL code linking against GPL libraries, certainly can be argued. Maybe that's something that they don't want to go to court to prove though.