Whatever the 'crimes' of this young woman, she is entitled to return home to face trial
I doubt if any justice system would, or could arrive at a decision to exile this or any British-born woman, even if she were found guilty - this is a sentence imposed on her by politicians - surely that is an abuse of her rights of as a citizen ?
This country has not exiled Shamima Begum. She took herself into exile. She chose to travel to a country in which the Foreign Office was already making clear there would be no consular support available.
If she were able to travel to the UK, and present herself at customs it is possible that she would be taken into custody, and then dealt with under UK law processes. But having placed herself beyond consular help I see no reason that the UK should be responsible for going out to get her.