Who on that list is a "renown epidemiologist"?
Jay Bhattacharya is a professor of Medicine at Stanford University, and a long-time researcher into public health policy: https://profiles.stanford.edu/jay-bhattacharya
Martin Kulldorff is a professor of medicine at Harvard University and Brigham and Women's Hospital, with a long history of research into epidemiological models: https://www.dfhcc.harvard.edu/insider/member-detail/member/m...
All of the authors are respected academics in the field of medicine, health policy and epidemiology.
> She is one of the primary authors of the Great Barrington Declaration, a widely-discredited paper[15] which advocated a focused response to the COVID-19 pandemic based on levels of individual risk.[16][17] The World Health Organization, as well as other numerous academic and public-health bodies, have stated that the strategy proposed by the Declaration is dangerous, unethical, and lacks a sound scientific basis.
Cool!
It’s not deductively valid in the same way that modus tollens is, but it is a often a good heuristic: the authority wouldn’t be recognized as such if they weren’t often correct in their area of expertise.
Thus, it’s fine to find an appeal “rationally compelling” as long as you bear in mind that the authority is also not infallible.
In this particular case, you brought up Bhattacharya‘s credentials. If another plausible expert disagrees with him, we’re at worst back to where we started; the fact that there’s a consensus he’s wrong, rather than just two dueling authorities, pushes back even harder.
That was true as of January 2020, it is no longer true now. I don't know about Gupta, but both Bhattacharya and Kulldorff (and Ioannidis) are being hated by most of their colleagues at the moment.
I would even conjecture - in 10 years, if you are a recent PhD/fellow from one of those labs, you will have a very tough time in the job market.