Some people try to make the world a better place. Your message is personal freedoms matters more than my beliefs. That is not true for everyone. Many will turn in their own mother to save themselves others will put their lives on the line to save your mother.
The other objections are about whistleblowing on private parties, discrimination or in one case a corrupt petty politician/magistrate. None of them would generate a safety concern to someone protected by Swiss law.
Seriously, the folks working the privacy angle on this story need to distinguish themselves from gangsters and organized crime syndicates. One person doing the wrong thing is bad; an organization doing it is a serious public concern and everywhere and always will generate a public response.
If you substituted Substack or a public-facing communication medium I'd be more sympathetic to the outrage at an email vendor complying with Swiss law. Here, however, we're talking about discovery of the identity behind private communications of an undetermined nature in compliance with the law of a mature Western democracy. Sorry folks, you've sometimes got to work within the democratic system to achieve your goals.
China could easily pressure an EU nation to make the request.