You've couldn't have posted a more conspiracy ridden blog post from a fellow conspiracy theorist, if you tried.. Classic pulling of sections that meet their conspiracy theory while ignoring the picture as a whole.
From reading the summary part of the FDA link it actually also states "Negative results do not preclude 2019-nCoV infection" - Which means it can be wrong about someone not having it also (correct me if I'm wrong). So that in theory also means MORE people may have it than we think.
Now does that mean results may be inaccurate, yes and it doesn't say what % that may be which isn't ideal. However, posting blog posts like that is again as with other things you've posted on here is extremely misleading, dishonest and dangerous.
The comments on the original blog post are just ridden with conspiracy theorists lapping it up too. The comments are the scariest part about it all. It does make me concerned about peoples mental health.
One of the comments is "COVID-19 is a giant global psy-ops and scam by our Overlords for their agenda of One World government, currency, military, and religion" - Like... what? That's the sort of reader that reads the blog posts you do.