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.)