The key point here is that NVIDIA's "everything always works" stance isn't just wrong, it's dangerous.
This doesn't just apply to the topic of this thread, it applies everywhere this stance manifests.
It's dangerous because a developer using NVIDIA hardware has a very real risk of producing a program that won't work on any other hardware.
It's dangerous because it perpetuates the situation where different OpenGL implementations behave differently and "To Hell With The Spec".
It's dangerous because it is a very real fact that OpenGL driver workarounds in programs will only continue so long as vendors are - and are allowed to be - lax with the spec.
This is damaging to OpenGL's reputation as a solid API. This is damaging to OpenGL's reputation as a dependable API. This is - in short - a classic example of the kind of nonsense that drives people to D3D.
It would be great to see future conformance tests be modified to check that things which are supposed to fail actually do fail.