Hi diverphil.
As a local from a Scottish West Coast island, now a pensioner, the lockdown you mention is fully supported by all who live and work in these remote places.
Because you are quite correct, our medical cover and the resources available are limited to the skill and dedication of 2 GP's and a couple of nurses, so if an emergency occurs then, well it can be quite a problem.
This is something we all have to understand, Folk have multiple jobs and we need to keep working, the livestock wont feed itself, the farmed fish need tending, ferries need to still run etc.
e.g. In the past I've worked the livestock, worked fishfarm boats, Driven local taxis, supplied animal feedstuff and when younger, flew air-taxis on the mainland for a time, everybody is in the same boat so to speak, and injures are unfortunately common.
(incidentally, these days more kayakers/divers are being lost than fishermen...sign of the times)
We also have an ageing population.
So if Covid-19 became endemic locally, then there wouldn't be the spare medical capacity to cope, the casualty rate could be a serious problem.
So, when when I suggest that a visiting yacht from parts unknown would be extremely unwelcome, it's because it could be a potential 'plague ship', so please nobody take offence if we ask the yachties to stay at home in the meantime...You'll be very welcome when it's over....