It is simply an example of Trump’s primary line of defense, that I call The Pee Wee Herman Defense AKA “I know you are but what am I?”
During the years 2009-2017, conservatives like Sean Hannity and random future MAGAs were screaming that Barack Obama was “NOT MY PRESIDENT!” Rush Limbaugh even tried to rebrand Presidents’ Day to “Not My President Day” (it failed of course).