blasphemers parent
That's not the case at all. His blog is his personal blog, not 37Signals, and he has never said employees were not allowed to share political opinions outside of work.
When you're the public face of a company you don't get to separate your personal political blogs from your work life. Your employees shouldn't know your political opinions and when you're that much in the public eye that means keeping them to yourself.
I genuinely don't understand why you believe this. Were you holding Bill Gates to the same standard when he still ran Microsoft? A charitable foundation is inherently political (it asserts the importance of the causes it financially supports, and holds them to represent matters of significant moral weight); should he not have put his and his wife's name on it?
this is in the same category as "the law in its majestic equality forbids both beggars and rich men to sleep under bridges".
DHH advocates "no politics at work" because as a powerful guy that's organized politics potentially directed at him. He advocates blogging because he knows perfectly well that he has a large audience and his employees or critics don't. That's why the rich tech bro class loves getting politics out of the workplace and getting it onto the platforms they own.