Earlier quoted context omitted.
When has that ever not been the case in the workplace? Every workplace has norms and values where someone who runs afoul of them may be fired. Norms change over time. There was a time when it would've been okay to use the 'n' word to insult black people in many work places, now it's not okay. There was a time when lewd and demeaning talk about women was ok in the workplace, now it's not. The people who sign the check…
The difference is senior leadership lying through their teeth about valuing diversity of opinion.
And there's also the question of how opinions are expressed. When you post something publicly for wide distribution, there's much less room to walk things back or to discreetly talk through things. Damore intended for his document to have impact, which it did. But that also means that if the impact is negative it's more likely to lead to his dismissal.
I'm not sure he should have been fired in this case but I can see why it was done.