In the 2nd link you posted Brendan Eich himself replies to you tell you to search for "constructive separation". So while he "quit" it didn't sound like he had much of an option.

I disagree with his views and believe Mozilla did the right thing in severing ties but I don't think it's as cut and dry as you're making it sound. It definitely comes across as a "We expect your resignation by the end of the day or shit will get messy for everyone" situation.