I'm pretty sure there are many ways to deal with such a situation and many ways to get it wrong. I'm not even arguing that what he did was right; given the amount of grief basecamp is getting, it's clearly possible to imagine a world where Jason had handled it better.
I don't understand though what "being a leader" means here, and why you're calling him a coward for trying out something, even if that something was wrong. What should a leader do if not try out things? Courage doesn't mean "do the right thing"; it just means don't be afraid. One can be a courageous asshole and a coward saint.
That said, you clearly have some ideas one how should one handle such a situation, and how to ensure political discussion don't lead to a toxic environment? Clearly justing saying "don't proselytise your political topics at work" is off the table for some reason.
What is exactly at stakes here? Is it about freedom of bring one's whole self at work? Is it about the urgency of solving the real and pressing problem of american society that requires everybody's attention everywhre? Is it a knee jerk reaction to the toxicity of the former presidential mandate that left a deep scar in american society? What are we talking about exactly here? Why can't I just feel free to mind my own business and do my javascript and whatnot at work and talk about politics at the pub?
I'm really curious, honest.