he pledged allegiance,
has anyone said he's been specifically recruited and planned by high up ISIS figures?
ISIS has repeatedly called for people to plan their own attack without help, and this certainly fits that bill.
I'm really not convinced that having no detectable links to IS and then blurting it out on the phone when cornered in a toilet makes this an IS attack. There's no particularly religious element to it, there's no evidence of radicalisation, this isn't some guy who went to a training camp and came back with a plan.
Anyone can commit an atrocity and shout 'ISIS' at some point, and they aren't the types of incidents that are going to be foiled by tougher borders.