Swiss courts are not something to be taken likely... since ProtonMail and its founders are based in Switzerland the employees themselves could have faced criminal charges for non-compliance.

A different argument could be made that they could be using more privacy-preserving tech that would make compliance not possible... but even then a court order + gag order could compel them to start logging.

Why this ruling is so important is it sets legal precedent that Protonmail is in the right to not turn over user data to the government. The Swiss legal system tends to be pretty firm about things and this will likely make it next to impossible for a repeat of their past fiasco to happen.