I wonder how police behaviour would be influenced by refusing to hand over the data? Will they assign less resources to your case because they think you're unhelpful by not turning over your data?
Rape is already under-investigated and under-prosecuted in the UK, and we've seen numbers of prosecutions declining alarmingly after the cases that caused this new guidance to be issued. So we don't need to wonder, we know: police and CPS administratively close the case.
How about everyone just keeps a secondary dumb phone to hand over when they feel that the police request is unreasonable.