If fell running was safe most of us wouldn’t bother. It is a large part of the appeal. Having said that being self reliant, and not a liability, is part of it and something runners should have learned if they are truly a fell runner. Weighing up the danger prior to setting off, and knowing your margins for getting out of trouble i.e. fitness level, knowledge of terrain, warmth of kit, should be obvious.
I got caught out in bad weather on the Mamores early this year with 2 others. It was severely cold and we cut it short. We knew escape routes and so new we would be as safe as is possible in February high up in Scotland. I wouldn’t have done anything different if I was Solo, but I may not have attempted such a long route, in winter, in the first place if on my own.
I would be embarrassed to need MR for almost anything other than a bad fall.