I agree - looking at the organizational directives I've worked on creating during my career, many specify that if you supervisor/manager/director does not act on an issue that is critical, that you are empowered to continue ahead and/or request followup.

There are more things and nuances specified, but the idea of "this is critical, but oh well my manager ignored me... nothing more I can do." doesn't seem to breed organizational success. (By no means I am advocating for insubordination per se.)

I was also talking about going up the hierarchy, but I'm afraid that he went to other bosses that made his division look bad.

I would never go public without going to a lawyer first, and getting enough proofs (emails) that I did everything I could to raise alert in a responsible way inside the company first.

Edit: after rereading the article I thing we just don't have enough data to know how things happened exactly.

With a company like VW (who has used engineers as scapegoats in the past), I'd just want to make sure there was a paper trail that indicates I did the right thing. Then I'd feel okay letting the business making the final call.