That can be interpreted in several ways. For example, the existing TAO capabilities have for long included installing a backdoored client application on target's mobile device (and only theirs) using vendor's regular update delivery channel.
In this case, the proposed UK regulations doesn't really change anything, it just makes it official requirement that the vendor must cooperate with the government in 1) deploying a backdoored client app, 2) delaying app upgrades for the target's device.
Of course, if UK government would like to delay updates for everyone for the sake of preserving access to one device, that would be indeed absurd. But I don't think it's the case, because the existing capabilities of the popular vendor delivery channels make selective delivery entirely possible and easy.
It seems the Home Office is annoyed it hasn't been able to stop tech companies improving people's privacy. They want to make it even easier to issue IPA notices. These notices can stop companies deploying security enhancing measures. https://www.bbc.co.uk/news/technology-66256081#privacy#encryption#RIPA