It's an international request from Europol. Switzerland is somewhat forced to comply with these (and this one in particular) for two reasons. One political and

It's an international request from Europol. Switzerland is somewhat forced to comply with these (and this one in particular) for two reasons. One political and one to serve its own interests. The political one is that if Switzerland in the future will create an international request countries could rebuff that in lieu of this very event. And to be honest I am not sure if they can refuse such requests after the recent referendum about abiding the EU constitution. The self-interest one is that those activists are/were prone to vandalizing banks which are a cornerstone of Swiss economy to this day (in smaller measure compared to the past since they now can pass information of account holders to other countries). Anyway, banks are still a big deal in the Swiss mentality and giving a literal "out of jail card" to someone that targets banks would set a bad precedent in Swiss public opinion.