That r2 value of 0.9995 is what was unsettling. You can probably fit at most 10 points for any quadratic process of natural origin so well, but not for 20 days straight?Just an idiot that doesn't know shit about epidemiology.
All he did was graph some numbers Excel and picked a quadratic model. There's no reason to pick a quadratic model in epidemiology. Disease growth is typically exponential. And when you do best fit, guess what: the parameters are forced to fit as best as possible. Any smooth function can be fitted by arbitrary number of polynomial if you pick enough polynomials and cherrypick the coefficients.
His model is y = Ax^2 + Bx + C. So why those particular numbers of A,B,C, and what do A,B,C mean? He doesn't know, nobody knows, because it's a shit and unphysical model.
From the Taylor expansion of y=Ae^Bx = A+ ABx + A(Bx)^2/2! + A(Bx)^3/3! +.... you can always pick A and B such that y = Ae^Bx ~ y = A + ABx + A(Bx)^2. You can always pick random numbers that make an exponential look quadratic.
Your knowledge of statistics seem to be more fresher than mine. What do you think?