So what happened?

Mr. Loukos’s work in Lyon has been much admired in the dance world. It “has long had an exceptionally ambitious and diverse repertory,” Roslyn Sulcas wrote in The Times in 2016. The following year, Alastair Macaulay, then The Times’s chief dance critic, named one of the company’s productions among the best of the year.

The current saga goes back to 2014, when Karline Marion, a then-34-year-old dancer, returned from maternity leave. Two days later, she received a letter saying that she would not receive a new contract.

Ms. Marion recorded a conversation with Mr. Loukos — later released by Mediacities, a French news website — in which he said that she had “done quite a bit” during her five years at the company, but that her best years were behind her. “Especially with a child,” he added, before telling the dancer to “stay in Lyon, go to the gym and look after your stuff.”

In 2017, a French court ruled that Mr. Loukos had discriminated against the dancer. Last December, an appeals court confirmed parts of the decision. The Lyon Opera Ballet said in an statement that it had then conducted an internal investigation that “revealed evidence that could be qualified as moral harassment” by Mr. Loukos.

The company fired him six months before he was due to retire.

The open letter to Libération was written by Maguy Marin, a French choreographer, with the aid of Ariane Mnouchkine, a theater director.

A spokeswoman for Ms. Marin declined to answer further questions in an email on Wednesday and did not respond to requests on Thursday to explain why the names of people who said they had disavowed the letter, or who had reservations about it, appeared in the published version.