I mean it's possible for sure, and there are a lot of historical predictions (like that French book) about a scenario like what you're describing, but I definitely wouldn't rule out the possibility of something more nightmarish like what I'm describing. I mean, I suppose the preps are pretty similar in both scenarios, but I think having some serious personal protective equipment, including P100 masks and lab style eyewear, etc. would be wise, as well as a lot more food and water than what most folks I've talked to consider to be "enough".