They can't quit Trump.
They need him to convince themselves that Biden, as a nice person, is a better alternative. This, even though any objective person can see that Biden is suffering from dementia and CLEARLY unable to perform the duties of the office of the president of the United States.
But mostly, they fear Trump.
They know if he runs against Biden in 2024, he'll crush Biden. (or Harris, as the case may be) So they're doing all they can to continue the lies they told about Trump for 4+ years.
They have nothing else.