the Isle of Man due to the small health system has locked down hard
I didnt read this as the reason. I thought it was because the IOM is a competently run jurisdiction that realised that leaving borders open as the UK did would lead to a pandemic. As scifi says, as a result
The interesting thing with the Isle of Man is that they haven't had a detected case of Covid-19 for 24 days. So it is almost safe to say that there are no Virus Particles left alive on the Island.