The reports I’ve seen (BBC, Guardian, Independent, so on) all seem to suggest that it is a creative use of the notion of dual citizenship. That they can make this move because she is
eligible for citizenship of another country. The suggestion (and it is no more than an inference that I’m drawing) would seem to be that this is not something she has already taken up. The Indy reports that the Bangladeshi authorities say she does not yet hold citizenship there.
I think we can take this matter out wider than Begum herself (as
Red Cat correctly advises
Spymaster). She herself bears responsibility for joining a movement responsible for atrocities, oppression, and all the rest of it, and for the effect the “Caliphate” had on the revolution against Assad. She undermined prerequisite solidarity in a grievous way. So, if she were to make to back to the UK, I’d say prosecute her. And I wouldn’t advocate helping her get back.
That said, this move would seem to be saying that because of a clever clerical trick we can make her Bangladesh’s responsibility. I’m not OK with that.
Nor am I OK with the precedent this sets. Revoking the citizenship of people the state has decided to disapprove of (including people who have not yet been convicted of anything) is not a healthy step. This is not about Begum. Frankly, to hell with her. This is about how far down the road this takes us to a point where this might in the future mean I can be stripped of citizenship if I go abroad on holiday, and while away, the state decides it doesn’t like the content of my bookshelves, as an example.
If Begum has broken UK laws, then try her in a UK court, should she manage to return. Don’t play to the gallery by trying to palm her off on a country that she *could* qualify for citizenship of. That opens all sorts of unpleasant consequences.