I'd say most suicide bombers want to kill themselves wouldn't they?
So what you are trying to get across it wasn't because of ISIS, it is a knock on event from the mentally ill guy hacking at people in the street? Had he not seen the media interest in ISIS then?
Now what? He had tried to commit suicide twice because of personal reasons. Had he succeeded he wouldn't have helped ISIS. ISIS suicide bombers want to die for ISIS, not for personal reasons. This guy was unusual as he had his personal agenda- which was not in line with ISIS normal policy. A leading Professor put this theory forward, that he decided to make use of his suicide wish which was already there. Sounds plausible.. But the investigation is ongoing.