As a writer, I tend not to ditch anything that I can alter or build around. If Memphis is TRICKED into breathing the microbe or someone is genetically enhanced to deliver it . . . [insert 17 other derivative ideas here] then that’s fine. As for the breath holding for 20 years, you should probably research spiders–they can ‘stasis’ themselves for longer, not needing to breathe at all. Then all you need is a tappable power source to maintain the forcefield, and you’re done.
There have been many times in my life I’ve thought putting myself in stasis would be good. Build the compound interest, save on food money, wait until I’m no longer ahead of my time . . . but you know that feeling, right? Good luck with the story. Put it up in the Writer’s Room here if you like.