I don't know about the specific incident in question, but it's not the first time someone has died on board, nor will it be the last.
If a PA was made for a medical pro to step forward, be it on a plane or anywhere else, I'd have my Paramedic ID in my hand and ready to show before I got anywhere near the scene.
Any MD on board who comes forward has to identify themselves, just as they would in any other incident, especially if they are going to take over from someone already tasked with providing first aid. A business card will do, a passport with a work visa (like the UAE) in it will also identify someone as a medical pro. (In a pinch medlink can be used to identify someone, but this takes far too long).
Any doctor or other pro who takes over without providing ID is leaving themselves wide open for all sorts of litigation, and they know it. These days, most medical pros will keep their heads down and try and avoid any impromptu medical work because of this.
On the other hand, I've seen Walter Mittys stepping in to the breach, loudly declaring their expertise, while trying to insist that the cabin crew force a stick down the patients throat to prevent them from "swallowing their tongue." (Gawd save us). It's because of these guys specifically, that some form of ID is required.
Many Docs haven't performed any kind of resuscitation in years. Unless they are working in an ER/A&E, they probably don't have to do so too frequently. Some 60 year old dermatologist may have gone decades without even checking for a pulse, so they aren't always that current or well practiced when it comes to CPR and ALS.
Regarding the crew: The training SUCKS. The first aid training covers the requisite topics, but the whole thing is geared towards passing a written test. Way too many crew treat it like a purely hypothetical exercise rather than something they might need to know some day. Most crew with prior medical qualifications have left these days, as there is little to keep them at EK, so more and more you get minimally trained crew who will only revise this stuff once every year before their recurrent training. When the **** hits the fan, you tend to see a massive rush of blood to the head (crew, not the patient), and they tend to focus on one thing only, the classic tunnel vision while under stress. Add in some passenger coming in claiming to be a doctor and the crew will likely focus on the ID component, as it is something easier or them to control.
At the same time, the other crew should be able to perform adequate CPR and get the defibrillator set up, but this is entirely dependent on which crew are present. Some would do a fantastic job, others would be cringeworthy.
The best help a Doctor would be at this point would be with epinephrine, basically injecting a load of adrenalin into the patient, or inserting an OP airway (no ET intubation kit or laryngoscope on board) to assist with artificial respiration.
The epinephrine and OP airways are kept in the EMK, a large briefcase style medical kit which contains a lot of stuff you'd hope to find on an ALS ambulance (except the ETintubation stuff), but is poorly laid out and is a bitch to find stuff in, especially when crew only get to have a look at it once a year generally, and pay little attention even then.
The suction unit is kept separately and takes a little practice to use. A Doc resident in a hospital may never have been near the portable hand pump EK uses, and may struggle to use it properly. Crew are not trained on it.
O2 flows at a max of 4lpm, which is pathetic in a resuscitation. Ideally a medical tank with 16-25lpm max should be on board.
Bottom line:
Any medical pro should be prepared to ID themselves at an incident, but it is incumbent on crew to do so quickly and without getting too officious.
The crew are trained to perform CPR and use an AED, but not all crew take the training to heart or understand why they need to know this.
The medical kit contains all the life saving drugs you'd hope for, but could do with a few more pieces of kit, as well as a much more user friendly layout. The resusc kits carried in first world ambulances would be ideal.