Because it's tying in two not-intrinsically-related concepts, namely, whether someone should lose their
living and whether someone should lose their status, authority, and power. These get tied together a lot in popular parlance.
In the article about the school principal linked elsewhere in the thread, the "fired" principal actually got a desk job elsewhere in the school district. I think that's a remarkably mature position to take (provided that compensation is not wildly lower): it's certainly excessive for that person to be unable to pay rent/mortgage or provide for his family, but not excessive to be unable to supervise children and teachers.
In the story about Brendan Eich, the CTO position was available for him to step back into (and available for him to have kept from the beginning). Even if we allow that he was forced out of the CEO role less than voluntarily, it seems much clearer that he left employment with Mozilla voluntarily, since there were no calls for his resignation while he was CTO. But it still gets reported that he was sacked.
In the story about Sir Tim Hunt, he resigned (possibly voluntarily, but no matter) from an honorary professorship at UCL, while maintaining his day job at Cancer Research UK. But the media spin is that he lost his job as a professor.
I would absolutely agree that people should not lose their living for a small mistake. I would disagree that any of these are examples of that, and I would strongly disagree that an employer should feel compelled to maintain public ties with someone they wish to distance themselves from, just because they feel an ethical responsibility for providing that person's living. That would compromise freedom of speech and association, namely that of everyone else at the company.