They'll know a lot more than we do and it is one of those cases that REALLY makes you take stock.
The thing I keep coming back to is that she was not been refused re-entry to the UK, was not summarily banned. But had to make her legal case to return from outside the UK, which is, as far as I can tell normal and was passed as legal by a court this year.
She is a radicalised woman with a husband who is an IS fighter whose letters exhort her to do what is good for their future. Nothing about what we know says she has shown any remorse, she just doesn't like the conditions and wants to come back...to what?
More of the same people seeking her out and making something more of a martyr of her, ensuring she remains radicalised, a threat? Prison, house arrest forever? A security risk forever?
She's no the only female to be made stateless. A very quick Google gets:
Aqsa Mahmood, Grace Dare, Sally Jones, all three Dawood sisters
And white males have been left in the same situation
Jihadi Jack (Canada might repatriate him)
There are 800 - 1500 UK citizens out there, with IS.
As far as the law, government is concerned this is about national security and not any one individual. And I am not sure that I could make a different decision about any of them!