Well it is about control they have to at least maintain the illusion that it's about child protection. They have to at least maintain the veneer of legitimacy. So if enough people make enough noise about how this is actually a privacy violating nightmare (even though that's actually the point) they will have to pretend to be concerned about that.

Anyway they have an out, this is mostly a Tory policy anyway that just got implemented under labour, so if it becomes a noose around there necks they can just get rid of the unpopular Tory policy and now they're the heroes.