On of the reasons, perhaps a less important reason ethically but nonetheless, is that China has breached the terms of the territorial handover agreement.
The agreement does not grant China full control to do whatever it likes over the territory at this time.
So legally, in response, Westerners in the form of the UK still have some kind of duty towards the people there.
A second reason, which I rank higher ethically, is that just by virtue of people existing, we still have a duty to demand better treatment for people who are being treated badly, especially when it's an imposed political event (and therefore can be changed) which is going to radically change their lives for the worse as they see it. Landmass connection or not.
The agreement does not grant China full control to do whatever it likes over the territory at this time.
So legally, in response, Westerners in the form of the UK still have some kind of duty towards the people there.
A second reason, which I rank higher ethically, is that just by virtue of people existing, we still have a duty to demand better treatment for people who are being treated badly, especially when it's an imposed political event (and therefore can be changed) which is going to radically change their lives for the worse as they see it. Landmass connection or not.