He wants to change the subject from banning oil and the Laptop from Hell.
The mask "controversy" provides Biden with a distinction from Trump and is a useful tool to deflect attention from Biden's highly questionable mental health, his and his family's crimes against America, his commitment to "fundamentally transform" our Republic into a socialist utopia and that his running mate (and likely successor when he inevitably falls apart) is an avowed, America-hating communist (and a very nasty person).