I can't answer your specific question, but there's a lot of DWS in Mallorca that's as safe as DWS can be and i'd be happy to do it alone. There's a possibility you could drown just like there's a possibility you could fall off a normal boulder, hit your head on a rock and die.
Freak accidents can happen but the risk can be very low if you choose sensible spots. Loads of surfers are happy to be out alone, but not so many who'd want to be out alone when it's double overhead!
Personally I think this is over-egging how safe it is on your own. A friend of mine fell off (seemingly not particularly weirdly, but hard to know for sure given upcoming events) and passed out under water while on their own. Fortunately it was brief and they regained consciousness before they drowned, but they spent 5 mins choking out sea water afterwards. Another friend broke a hold off while really high up (20m+), smashed in to a ledge and then hit the water. If his pals weren't there to swim him out I think there's a fairly decent chance he could have died. Then of course there is the Cook brother who died while DWSing on his own in Mallorca.Having said that I've done quite a bit of DWS on my own, but I think you need to be aware that if you fall off badly in the wrong place it's more risky than bouldering, because you're in the sea which means it's easy to drown.
I remember opening my eyes underwater, not being able to see anything, and not knowing which way was up. Next thing I remember was being back on the surface but having the distinct feeling that I was watching myself struggling and vaguely feeling that I should be trying harder to stay alive but didn't have any control over my actions - I suspect this is the kind of thing that gets called an out-of-body experience.
As others have said, bloody hell!!! Scary stuff. Whether or not cold water shock was involved it's worth saying that acclimatising yourself to cold water really works. If you know you're going earlier in the year when the water's going to be a bit cooler it might worth getting some swimming in before the trip.