The article didn’t but for context german elections are happening in a couple months. I think the perpetrator wanted to portray immigrants as bad or that immigrants are attacking german values/culture.

The attacker was an ex-muslim, pro afd and anti-islam, and anti-immigrant activist.

In many ways, he was similar to the person you replied to.

Edit: you know whats funny? If this attacker was pro islam, you would see it in the headline