I think this story takes on a particular valence because it involves a libertarian-inflected business in supposedly left-leaning SV. Certainly most of the HN commentary has jumped to the assumption that this is the result of pushy SJWs etc.
But I don't think this is a good way to approach political speech at work. Coinbase is aligned very closely with libertarian politics for a variety of reasons that complement each other. I would be very surprised if there wasn't rampant libertarian-inflected speech being traded by employees. Indeed, a policy against engaging in political speech unrelated to the company's goal will almost certainly amplify that particular type of political messaging.
I work for a company with very conservative leadership, who contribute, individually, to very conservative causes. I contribute to and participate in a Pride event being held in my town. Last year an outside political group protested the event, and it led to the City, via the city council, chaired by the CEO of my company, creating de novo restrictions on usage of City property specially for that event, and my boss showing up to film that event. Later, the same political group ran a political candidate for mayor explicitly on a ticket of shutting out Pride from City facilities (which, obviously, is legally dubious). It was a rancorous election in a deeply conservative community, even though the challenger got nowhere near the votes required to win.
My company's official policy is that, in the interest of respecting others, we should refrain from discussing politics at work. In the context of this election, my coworkers, with whom I share a pod, were discussing how the city should just be able to kick out Pride, because it's fine if people are gay, we just don't want them in our community. These same coworkers often waste their time quoting Steven Crowder and similar political talkers. My manager, who works in the same pod, initiates conversations every week about, how was your weekend, what did you do. I find them uncomfortable, but my manager sees them as valuable for team building.
Generally I find my team fairly collegial, though they almost certainly don't share my political or, in some cases, religious convictions. During the week of Pride I mentioned I had attended the event with my wife, and I received cold looks from the entire office.
I am frequently looking for work elsewhere, for a variety of reasons. And if I were offered a buyout this generous I would definitely take it.