What a ridiculous analogy and I suggest you take the training that dispatchers must go through or learn CPR better so that you can talk someone through it as it might be necessary for them to assist you sometime either on or off the job. If you are the only one that is CPR certified and the ambulance has a 15 minute response time, good luck doing CPR that long properly and effectively by yourself.
LEOs are trained to talk people through difficult situations and doing effective CPR would qualify for a difficult situation.
Dispatchers talk parents through CPR and other emergency procedures everyday without ever seeing the scene. There is data to back up their abilities to get people to do what needs to be done in an emergency with the proper coaching. But then, looking at some of the threads on the EMS forums, it is easy for some to think learning CPR is very, very difficult.
When you get to a scene that might have the potential to be very unsafe like an unstable car or the patient, a child, is lying in traffic, do you rush right over or do you secure the scene especially there is already someone with the patient who can do some CPR or first aid? Even though your first instinct and emotional response might be to disregard safety and just rush to the patient, you must remember EVERYTHING about your training. In this situation someone was already able to do CPR effectively with a little coaching which allowed the LEO to focus on the entire situation where there might have been other concerns.
I can almost guarantee that if the LEO was focused on patient care by doing CPR and the EMTs' response was slowed or one of them got injured because he wasn't doing HIS JOB as an LEO, those EMTs would have their attorney on the phone screaming to sue him and demand he be fired. They would probably also forget all about doing CPR and start typing on some EMS forum about how negligent the LEO was.