I work in infosec, and this sounds like a communication failure on the whistleblower's part. Contrary to what many people believe, the profits should be prioritized over security for the most companies, that's only natural (after all, they don't generate any profits themselves, typically). The key is finding the right balance for this tradeoff. Business leaders are the ones that are responsible for figuring out the a…
Why not go even further? Why not say that the whistleblower was wrong and Microsoft business leadership was right? Maybe their profits from ignoring this issue have been fantastic, and the externalities from e.g. mass theft of national security secrets are not Microsoft's problem.
I highly doubt that the senior leadership would willingly accept this kind of liability. But you need to put it into right terms for them to understand. Politics play important role at that level as well. There are ways of putting additional pressure on the c-suite, such as making sure certain keywords are used in writing, triggering input from legal or forcing stakeholders to formally sign off on a presented risk.
Without insight knowledge, it's impossible to figure out what went wrong here, so I'm not assigning blame to the whistleblower, just commenting that way too often techies fail to communicate risks effectively.