Aggressive stances towards deportation are the consequence of inaccurate arguments that immigrants are on average unwelcome freeloaders and destroyers of job value rather than making the future of the country more sustainable though. It's entirely possible for immigrants to have security of tenure and actually more desirable given declining birth rates: it's the assumption that our current society would be more sustainable in their absence which drives governments to make it as difficult as possible to obtain/retain.

All the rhetoric which drove repatriation of the Windrush migrants [a much more representative case than Begum leaving the UK to join ISIS] was based around the popularisation of the idea that the UK was 'full' of 'unsustainable' numbers of migrants. So it certainly doesn't help immigrants to pointedly refuse to state reasons why this is incorrect.