If I may chime in hear again, homing in on general prinicples of fail-safe flying:
if you asked most commercial pilots both today and in 1979, would there be/have been a consensus that a visual descent below MSA must ALWAYS be preceded by something more "positive" than the unquestioned assumption your (actual !!) AINS flight plan, unaccompanied by any additional crosschecks or corroboration, could not possibly be fallible? The "Vette" position would appear to say no, not always. Isn't this essentially what the debate reduces to?