Think of this:
In radio, only one thing matters: RATINGS.
As Donald Trump is currently the legitimate POTUS but denied executing the duties we the American people have bestowed upon him, the next best thing he can do is COMMUNICATE with us, through the power of radio, a medium that long outdates Twitter and any other social media.
With GEOTUS occupying our time from Noon to 3pm ET each weekday, Americans can keep abreast of what's going on, and what we can do to Make America Great Again.
They can build a studio inside Mar-A-Lago, and although he won't have live spectators like he had at his concerts, he can possible TALK with them, and have on important guests, including loyal senators and congressmen for interviews. Imagine him talking with Matt Gaetz or MTG or Louie Gohmert or whomever about what's really happening in Washington.
I cannot think of another single person, more experienced in broadcasting, who can step into Rush Limbaugh's shoes.
he's a billionaire
he literally has 1000's of better things he could be doing
watching gorilla channel for instance
He already said "Nobody wants to follow Rush, he's irreplaceable"