I would say it depends on how bad the mud is. It is hard to tell in the picture. I think if it were me I'd just hang on and see what happens during the next few days or longer. I have kind of two thoughts, one is if there is mud after two days it might be worse after a week or more, on the other hand we are heading into summer which of course means dryer weather. Now take someone like me. I've got about 40 chickens, and two huge runs for all these chickens. There is no way that I can really control all of the mud in the pacific northwest during the rainy season. So I make sure there is some place they can go that is dry, and places with dry dirty so they can dirt bath, but there is still mud and I'll never get rid of it. I guess what I'm saying is mud isn't the best thing in the world for the chickens, but it isn't going to cause them any great harm so long as they have sufficient non-muddy areas to be in.