Daft idea because it would cause many more problems than it solved. How many cases have there been of single police officers falsely arresting a woman so that they can abduct, rape and murder them? One? I can't think of any other similar cases, and they're the sort of thing that gets a lot of attention on the news.
If you say single officers can't detain women, it's the start of a slippery slope. What if the officer is homosexual, should he avoid arresting men too? Perhaps the officer is racist, so no single officer should arrest BAMEs. Look out, here comes a female officer, she can't touch that gangster in case she sexually assaults him?
The problem with the Everard case, the problem with the Nessa case, is that the publicity they (understandably) receive makes women more nervous than the reality suggests they should be. This leads to daft suggestions like men shouldn't be allowed out after 6pm and police officers shouldn't carry out an arrest if they are alone. We need to assess risk based on facts and evidence. The facts are:
a) I'm much less at risk of being attacked and murdered than a man (men account for about 80% of murder victims).
b) I'm much less at risk outside in public than I am at home (the vast majority of murders of women happen in the home or other "safe" place).
The perception of women being at greater risk is just that, a perception that is not bourne out by the facts. If you see a lone policeman walking towards you in the street the chances are he's exactly that, a lone policeman who happens to be headed in your direction. If a man walks behind me in an alley, great - I know that most men aren't going to attack me, and any would-be attacker hiding in the bushes will be put off by the fact a man is behind me.
Seeing bad things on the news doesn't make them more likely to happen to you - and neither does risk vary by the amount of coverage a story might receive.