Bloody hell.
I reckon a HT who shows such appalling judgement should be sacked. She has failed in her duty of care.
The second link in the OP didn't work for me, try here. At least the authorities are dealing with it now its been brought to their attention.
Makes me wonder what would have happened if it had been a 'Free school' - I have misgivings that they could provide an open door to these extremists.