It's a no-win situation for Fauci and the CDC right now. The problem with fighting an invisible enemy like this is that, if you do everything perfectly, it looks like you made a whole lot of noise about nothing. And if you don't take decisive action, hundreds of thousands of people die - many more than would have if you had done everything perfectly, and probably by orders of magnitude.
When we first decided to start putting safety measures in place around COVID, people bitched about how it was going too far too fast - the scientists were exaggerating, it's just a cold, old people always die, everyone needs to calm down. And in retrospect, I'm sure the management side of that public communication decided they needed to be a little more reserved and not give in to sensationalism or hyperbole, so it's not a surprise that they are being more reserved in communicating the degree to which they probably feel like the Delta, Delta Plus, or Lambda variants are putting people at further risk. To your point, Crouton, I wouldn't be surprised to find out that they can intuitively say to themselves "this seems like it's going to be an issue, but we need to get the data before we make this public in order to avoid past communication pitfalls."