"SpaceX, the private rocket company, on Thursday fired employees who helped write and distribute an open letter criticizing the behavior of chief executive Elon Musk, said three employees with knowledge of the situation."

First paragraph of the article.

And of course there is also this, "In an email, Gwynne Shotwell, SpaceX’s president, said the letter had made other employees “feel uncomfortable, intimidated and bullied.”"

That doesn't answer the question, obviously. An open letter shared in a private medium is not public. I get the impression that neither the general public nor Musk himself were the intended audience of the letter.

I find the entire notion of calling for the CEO's ouster with "tact" a bit disingenuous.