Willard was arrested on July 18 for alleged "lewd conduct" at an adult movie theatre in Los Angeles.
The 72-year-old has since denied the charge, claiming that the arrest was a "misunderstanding" between himself and police.
Deadline reports that at a recent TCA presentation, CEO Paula Kerger addressed the veteran actor's release from the PBS reality show.
She explained: "We are actually in production with that series, and at the end of the week when it became known, we realised we had to move fast because we are taping now, it's a new series.
"His circumstances would have become a distraction to the series."
Antiques Roadshow host Mark Walberg has been tapped to take on Willard's role as narrator of Market Warriors.