As with all these things there is loads you just don't know and as usual the Rib Net Police are in overdrive.
Who did he offer his assistance and how? Did he pull alongside the yacht offer help and be told its OK lifeboat's on its way and the leave? Feels like the thing to do if you are only 50m away. Or did he offer assistance via VHF and therefore Solent CG either decline it or allow him to leave the scene - feels like something they are less likely to do. I might have been expected to standby nearby incase the picture changed but that the LB might be a better evacuation option? They know there is space to lie a casualty down on a LB for instance - not much fancying hanging onto a rib tube with only 1 hand!!
Taking a while to leave in an ambulance does not mean its not life and death. Scoop and run is only used if the ambulance crew dont have the ability to stabilise the patient. Full expect it to have been re-dressed, pain relief, IV access incase needed etc. In addition its pretty common to have a doctor on a lifeboat crew so the doc may have been waiting with the ambulance crew and therefore been doing some assessment in the ambulance.
The situation on the yacht is not fully known/described - how many other crew. Were they competent to get the yacht back ashore without the injured person.
Its been said time and time again on here if in doubt make it a MayDay and down grade it later. You can't upgrade it if ur dead...
Or to put it another way - if I was at home and cut my finger off and had no means to quickly get to hospital I wouldn't feel it inappropriate to dial 999 for an ambulance. Technically I could call a taxi. I wouldn't expect any ambulance service to think it was an inappropriate call (trust me people call for far far less serious!!)
Wouldn't think it made any difference what resources were allocated to the call.