Yes Keith,no one is disputing ISIS claimed responsibility for the incident.
What we are saying is they did not carry out the attack.
They possibly encouraged some local sympathizers to do so.
Those people could have done the deed anyway,they were not armed or trained by ISIS.
ISIS claimed responsibility to give the impression to the gullible that their power extends to anywhere they chose.
The idea of terrorism is to spread fear and cause disruption to normal life patterns.