The storyline was criticised by Alena Smith, a Newsroom writer, who posted a series of comments on Twitter.
Responding to Smith's criticisms, Sorkin said she had "casually violated the most important rule of working in a writers' room, which is confidentiality".
Sorkin told Mediaite website: "After a while I needed to move on ... but Alena wasn't ready to do that yet. I gave her more time but then I really needed to move on. Alena still wouldn't let me do that so I excused her from the room."
Smith had made vocal objections to the plot - but "gave her enthusiastic support" after Sorkin had rewritten the screenplay, the screenwriter of The Social Network said.
The episode was derided by US critics. Emily Nussbaum, of The New Yorker, wrote of the producer: "He argues that the idealistic thing to do is not to believe her story."
Sorkin argued: "I understood there would be backlash - some thoughtful, some of it less so - but that's a bad reason not to write something."
* The Newsroom screens on Soho on Thursday at 9.30pm.
- Independent