Proton should look who was asking the disclosure. He's a known far-right judge that opens cases like beer cans. And the "terrorist" group is marked as such because someone had a heart attack the same day there were protests in Catalonia.
Does it matter? He's still a judge with a judge's authority. If their policy is to obey the law then the political views of the judge don't change the fact that his order was lawful.
A Russian/Chinese judge ordering the disclosure of data about a Spanish citizen? Then no, because judges from one country should hold no jurisdiction over citizens of other countries (unless it's about things these citizens did in the judge's country - which is not the hypothetical case here)
A Russian/Chinese born person who became a judge in Spain? Then yes, because the judge's ethnicity should not be a factor on whether or not their authority is respected.
A Russian/Chinese judge ordering the disclosure of data about a Russian/Chinese (respectively) citizen? Then this depends on whether or not Proton Mail is willing to stop doing business in Russia/China (again - respectively). Though I'm not sure if that will save them, since it may still be possible, even after the cut ties with that country, for the government to go after them using international treaties.
At any rate, my point is that the decision of whether you obey the law or protect your users should be about the country as a whole, not about any specific judge employed by it. Choosing to obey some judges of the country while ignoring the warrants signed by other judges of the same country is just stupid. The country will not trust you to respect their authority and will not permit you to do business there, while the users will not trust you to keep your promise to protect them and won't use your service.