An ex-Facebook executive sat in silence during a panel discussion about her tell-all book about the social media giant because of ongoing legal action by her former bosses at Meta.
New Zealand-born Sarah Wynn-Williams was introduced as "an author in a hostage situation" at the Hay Festival, Powys, on Sunday.
She is under threat of further legal by Meta if she does anything to promote her book, Careless People, explained investigative journalist Carole Cadwalladr.
Meta denied trying to "silence" Wynn-Williams or restrict her freedom of speech, adding an interim order prohibited her from book promotion.
Cadwalladr read part of a letter from Wynn-Williams' lawyer, explaining their understanding of her legal predicament.
"Meta obtained a temporary order preventing Ms Wynn-Williams from promoting her book or speaking about certain topics regardless of whether what she says is true," it said.
Cadwalladr appeared with Wynn-Williams and academic Tim Wu at the event.
Wynn-Williams is one of the most senior former Meta executives to speak about Mark Zuckerberg.
Wu called the lawsuit a "machine reaction, not a personal vendetta".
He accused Meta of "maximising the punishment" as a warning to any other would-be Meta whistleblowers.
"This is performative," said Cadwalladr.
Wu, a professor at Columbia University in New York, who was involved in the Obama and Biden administrations, called it "censorship".
"This is the age of private censorship, this is the assertion of power, a...
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