To try to give a reasoned answer: there must be limits. And the limits will always be somewhat arbitrary. But the limits implied by Google's actions are clearly unreasonable in two ways:
1. I agree we should not allow racial slurs, or Nazi symbols, etc. We can do that because the vast majority of society disapproves of them. But the opinions in the document are not in that status: they are mostly rejected by progressives, debated by centrists, and mostly accepted by conservatives. In other words, Google has sent a signal of "you can't work here if you're not a progressive", and that's harmful on a societal level, because while we can have a functioning society after kicking out Nazis and people saying slurs, can we thrive if we have separate corporations for progressives and conservatives? No, we have to find a way to work together. Google's actions were a blow against such cooperation.
2. Saying that average group differences exist is a scientific fact (there are debates about where the differences lie, what they mean, what caused them, etc. but that some exist is long settled). And just acknowledging their existence seems to be what got this person fired, after others - including Google leadership - misunderstood average group differences to mean "one group is inferior to another".
