After my initial outrage, I calmed down and looked at this dryly. What if the main issue is that the prosecutors just do not have appropriate mental models of hackers?
The crucial step is that they wanted to get ahold of Riseup, a mail provider (and hence, in their view, a commercial entity). Then they find those German people (whom they can get ahold of) who collect money for Riseup. I find it very likely that they just could not imagine someone collecting money for a commercial entity without being financially and personally intertwined with said entity.
For example, if you see someone collecting money for Coca-Cola, wouldn't you think that they're paid by Coca-Cola, no matter how much they insisted they're "just fans"?
(Note: This argument only concerns the original warrant. What the policemen did at the hackerspachackerspace was just preposterous.)
If you are directly or indirectly paid by a company, then it is unlikely that you have sufficient amount of operational information at home to warrant searching your home.
Worse, if you suspect that somebody's role is related to fund raising then it very unlikely that that person has detailed operational information.
To the extent that the police is aware that riseup is a US-based organisation, then any kind of forced cooperation the German police would get from the people outside the US would unlikely to have any effect, because a US-based organisation is likely to only respond to requests from a US police organisation.
So this kind of action can only be explained by criminal carelessness or a goal to intimidate.
Additionally, while Coca-Cola is a company, Riseup is a non-profit, Openlab / onionfriends are also non-profits. They have volunteers, with a mindset shared by both groups. I assume volunteers will often help at multiple non-profits (spin-offs, etc.). Starting with the people that already have a connection and shared mindset is logical.
The crucial step is that they wanted to get ahold of Riseup, a mail provider (and hence, in their view, a commercial entity). Then they find those German people (whom they can get ahold of) who collect money for Riseup. I find it very likely that they just could not imagine someone collecting money for a commercial entity without being financially and personally intertwined with said entity.
For example, if you see someone collecting money for Coca-Cola, wouldn't you think that they're paid by Coca-Cola, no matter how much they insisted they're "just fans"?
(Note: This argument only concerns the original warrant. What the policemen did at the hackerspachackerspace was just preposterous.)