> Just using encryption leads to this?

No. The people arrested in that case were anarchists and had varying levels of engagement for social change. The main defendant, who this article talks about, was a vocal opponent of the State and state-sponsored injustices (police abuse, social inequalities, etc).

Whether he actually planned attacks against the State as he is accused of, i don't know although the fact all the accused were liberated tends to show the police had nothing against them. But even if these police fantasies were true, any damage he could do by attacking eg. a police station would be nothing compared to the millions of people who suffer/die every year do to french imperialism and its racist and ecocidal policies.