Internet norms are only internet norms, they aren't everywhere norms. Cade Metz did not "doxx" Scott Alexander, because doxxing does not exist outside of some particular very online spaces. And Alexander even wasn't doxxed by properly-understood internet norms because he doxxed himself long before.
The situation was Scott Alexander was confused to think the norms of his community were controlling in every community, or that he could set arbitrary rules that everyone else would then be obligated to follow, and he has a lot of fans who share those confusions.