If I was making the rules, I'd be in favour of allowing some extra time for finishers in those conditions. But not just because it was cold/windy.
Then exactly why? If it hadn't been cold and windy most would have finished...
Firstly, kudos to everybody who made it to Oxford, or even past Chepstow. As was I packed soon after (mechanical, gov, honest) but suspect the biggest factor was the biting cold headwind. The snow was just the icing on the cake.
I'm generally agin weather concessions. They rather undermine the whole spirit of what we do. All events are run to the same regulations and dealing with the weather is part of it, so why should one event or set of conditions be deemed more worthy than any other? Your pleasant summer day might be my heatstroke? How would concessions be managed for Perms? And so on. It's a can of worms best left closed.
Being audacious is about setting out with a sense of adventure, knowing there's a risk of failure and dealing with it. If you achieve your goal, great, if not then there's always next time, and the achivement will be the greater. For events like PBP and LEL other considerations may apply, but everybody who started the Dean had a very clear idea of what they were getting into.