From what I gathered from a (French) blog posting by a squatting collective, posted elsewhere in this thread, the arrests are in relation to an eviction.

The eviction was legally sanctioned, and violence was used on the officers. Several officers had to stop work for a few days, one officer for two weeks.

I myself am a middle-aged "have" , but I do worry about climate and I do empathize with those that "have not".

However, violence during an eviction is not peaceful. People were hurt, and a legal response was due. Seems to me that arresting someone after the fact, and dealing with the matter in a court of law is the peaceful thing to do?