I say "goes by" because "Scott Alexander" is a pen name. The blog he writes touches on many different topics, from science to current events -- I would generalize it as "philosophy". And "Scott" has always written it under a pen name for a few reasons: to keep his private life separate from public controversy being one, but also because (he claims) his livelihood as a practicing psychiatrist is not compatible with maintaining a public persona.
The New York Times chose to write a story about his blog. And they intend to publish his actual name, over Scott's objection.
Is this ethical? There is a great deal of value in people's ability to communicate anonymously. It allows people to take positions and raise issues that they otherwise could not. That is why the ability to speak anonymously has always been enshrined in US law and protected by the First Amendment. Now, this doesn't make it illegal for the New York Times to publish his name if they find it out -- but it certainly suggests there is value in allowing people to maintain privacy.
There are certainly cases where the true identity of an anonymous writer would be important news. If the New York Times were to discover that a leading blogger supporting Donald Trump was actually a pen name for Joe Biden, that would be important information that should be disclosed to the public.
But if it is not newsworthy? If revealing the identity of the individual does not serve an important function? Then it is a case of harming an individual (potentially taking away -- at least partially -- their livelihood) for no real public benefit. In my opinion, that is not ethical.
Scott Alexander claims that the New York Times reporter says the choice to reveal the blogger's identity was at the insistance of his editor -- that this is official New York Times policy. I believe that to be a failure of journalistic ethics. Which is why I am calling today to cancel my New York Times subscription.