Your story reminds me of when Microsoft acquired Hotmail in the '90s and they tried migrating from FreeBSD & Solaris onto Windows NT/IIS. Having the world's largest email service running on the Windows stack would have been a huge endorsement. It took years until they were successful.
https://www.zdnet.com/article/ms-moving-hotmail-to-win2000-s...
https://jimbojones.livejournal.com/23143.html