Coronavirus quarantine seems to have Seth MacFarlane more willing than ever to speak out against powerful figures in the media.

Last week, the Family Guy creator took on Fox News host Laura Ingraham for her relentless campaign to end the stay-at-home orders. Now, he has Oprah Winfrey in his sights.

“Oprah has done some wonderfully altruistic things with her career, but the use of her platform to amplify the voices of dubious characters rather than legitimate scientists has been a disservice,” MacFarlane tweeted recently. “I hope she will lend her own powerful voice to correct it.” He included a link to a Los Angeles Times article that broke down how Dr. Phil McGraw and Dr. Mehmet Oz—both of whom rose to fame via Winfrey’s show—have been spreading medical misinformation during the crisis.

Asked about his tweet on the first episode of Vice TV’s new political talk show Seat at the Table with Anand Giridharadas, which will air Wednesday night, MacFarlane reiterated that he believes Winfrey has mostly “used her platform for good.”

“The exception to that is the elevation of these purveyors of pseudoscience. People like Dr. Phil, Dr. Oz, all the way back to Jenny McCarthy and the anti-vax movement,” he continued. “And it’s a strange dichotomy that I think a lot of people, particularly right now, are having trouble reconciling. You know this person who has done all of this positive work for the world and yet somehow has gotten caught up in this web of junk science on many occasions. So, it’s a tough thing to balance.”

Two years ago, after Winfrey’s galvanizing Golden Globes speech led to rampant speculation that she could challenge Trump for the presidency in 2020, MacFarlane explained why he thought that would be a terrible idea.

“Oprah is beyond doubt a magnificent orator,” he tweeted at the time. “But the idea of a reality show star running against a talk show host is troublingly dystopian. We don’t want to create a world where dedicated public service careers become undesirable and impractical in the face of raw celebrity.”

With Family Guy, American Dad, and other projects, MacFarlane has spent almost his entire career working at the Fox corporation, and making boatloads of money for the Murdoch family, which also runs Fox News. He said he maintains a “friendly” relationship with the Murdochs despite their deep political differences, adding that they have never tried to censor his shows.

“They’ve left us alone completely. Even when our politics were aggressively liberal,” MacFarlane said. “And the same philosophy as far as I can tell applies to Fox News.” At the same time, he said he wishes the Murdochs would “take a more active role” in policing Fox News content.

“If that network could get on board with a responsible attitude toward science alone, I could live with all the other shit,” he said.