Would you post a link to the WaPo article that has Fauci saying that the reason he said masks are ineffective was to preserve the supply for medical staff?
I would be ok with Fauci saying masks weren't effective because the best science avialable was incorrect at that time. Science can be flawed, especially early on when facing a new disease. We might not know if the virus is surface spread or airborne. We might believe that it is transmitted through droplets after a cough - something medical staff would experience much more of than people at a grocery store. There are all kinds of reasons they could be wrong. So the CDC, and Fauci, would lose no credibility with me merely by being wrong, in retrospect, if they were presenting the best answers science had that that time.
Now, if the CDC deliberately misled, then it absolutely isn't fine. The CDC has authority because they are scientists. We respect and follow their advice not because we believe they are our noble leaders, or our moral betters, or know best for us, but because we believe that what they say is the truth, grounded in science. If they in fact used this trust to deliberately mislead, it would be devastating to his credibility and the credibility of the CDC for a very, very long time. For our own benefit? Perhaps, but it would still be a deep betrayal of his specific office because of the source of his authority.
The CDC could say, in that case, "we believe that masks are effective, and N95 medical grade masks are best - however, there is a shortage right now. Because cloth masks can provide some protection for essential activities such as grocery shopping, and medical grade masks are essential for medical providers who will work in close proximity with many infected people, we implore the American people to allow all medical grade masks to go to medical providers, and we support regulations that require these masks be reserved for medical providers".
That would be fine. But you can't represent science and truth and then lie about the science. Not if you want to be trusted ever again.
To be clear, these are scenarios. I'm not sure it's entirely established that Fauci clearly knew that masks were effective for day to day non medical use and deliberately told people the opposite in order to keep them from buying masks. I've done some reading, and Fauci stumbles a lot over this - he keeps saying two things at once - that it wasn't clear that a masks were important, and that we badly needed to reserve them for medical personnel. The second statement actually badly undermines the first, IMO, because it would provide a justification for lying (even if this isn't what he did).
Anyway, if you have that WaPo link, please send it. That would change how I see this situation.