Police being close by in a big city like Hamburg isn't such a weird coincidence tbh.
But German police and secret services dropping the ball on mentally ill dangerous people isn't news.
I vaguely remember one or two Muslim terror attacks where they had info but didn't act, an attempted storming of the Reichstag by right-wing schizos that was announced in advance but no preparations were made by police, etc etc.
But raiding homes of lefties for calling some local politican a dick is something they do very quickly for some reason.