Setting aside the question of "should Internet have reacted like it did" - the reality is that her employer had little choice, given the circumstances. Yes, it was "outside-the-community behaviour", but the business impact was immediate & considerable, I argue that for the employer there was only one reasonable/rational way to handle the crisis.
[edit] Or to take a somewhat extreme hypothetical example - I presume that if you found out that, for whatever reason, a prominent Mozilla exec was secretly funding anti-Net-Neutrality lobby (i.e "out of the community behaviour"), you would expect Mozilla to talk about it and "handle the issue", not just say that "sorry, his own money, his own personal time, he can do whatever he wants to".
What if you find out that the other other person supports strong enforcement of existing immigration laws? What if supporters of that policy are being labeled as a "white nationalists" by others? Is that really evidence of "white nationalism"? What if that person simultaneously supports significant changes to the immigration laws that would result in more legal immigration?
If the answer is no, I would kick them out just the same and that's ok.
People who are actively sharing white supremacist screed are not nearly in the same category.