You have some data in the hands of any government, and once you have a judge's approval, the data will be obtained by the authority regardless where you are. It makes sense that the data should be stored on your devices only. If a criminal is caught with his phone, the data can still be obtained by the police (the same as phone records for example), and it can still be useful for criminal investigation, and normal citizen don't have to worry about their data. It is actually achievable with Google and Apple's approach.

And I think it was a genuine answer. This is a reply to MP, not a random reporter on streets.