Could be there are good breakthroughs/treatments becoming available and/or alternatives to the methods Birx and Fauci are pushing.
MSM has to inject ridicule at the first indication that the Overton window is being widened in that direction. It's what they do. Shows more than anything that the MSM was surprised and had to resort to the ridicule to try to buy time. Stuff like Pelosi's and Warren's statements shows they're just pulling shit out of their ass at this point. Gross mis-characterizations.
POTUS uses the ridicule as a type of Streisand effect. SM will take over the narrative as people explore the alternatives and discover the MSM cover up attempt. Too late at this point for the MSM to counter effectively, IMO.
POTUS's goal is to break the "Government Bureaucrat Expert" fallacy.