Don't you think it makes sense that as we learned about how the virus spreads, and as the number of people infected exploded, that the mask recommendation might change?

I think you're trying to mock scientific experts, but what kind of expert would NOT be willing to change their recommendation based on new, strong, contrary information?

Of course experts would prefer not to make a recommendation until all the facts are known, to avoid being wrong. But that simply was not (still and is not) possible with the pandemic.

We have to decide how to react with the information we have and it's just rational to be willing to change our decision based on strong new information.