Earlier quoted context omitted.
Also, as pointed out elsewhere, people (or the general sentiment) on these discussions seemed to be all in favor of firing those who hold unpopular / conservative personal opinions, but now disagree with firing those with liberal opinions. If that's not viewpoint discrimination, I don't know what is.
Nobody's getting fired for suggesting the top marginal tax rate should be lower, or expressing the value of hard work and individual responsibility. The apparent phenomenon you allude to is the result of the normalization of sexist, racist, and xenophobic beliefs within the "conservative" sphere over the past few decades. Those beliefs are incompatible with being a member of a pluralistic workforce.
No, the opinion to watch out for is the one who fervently believes that it is the arbiter of what is socially acceptable to say, and is the interpreter of the rules by which it's enforced. Dare to raise a topic of discussion that is even tinged by the topic of sex, race, etc, no matter how important or worthy of discussion, and you'll be labeled offensive and worthy of being fired or banned. And this opinion never ceases believing its own righteousness, that's the worst part.