The reason eggs would be unsafe is that bacteria gets inside them and multiplies. If bacteria doesn't get inside, it can't multiply.
About the last thing a hen does when she lays an egg is coat it with what we call "bloom". That's why an egg looks wet as it is being laid. That bloom quickly dries and forms a barrier that is so effective at keeping bacteria out that the hens can lay eggs in a hidden nest for two weeks and then incubate them for three more without bacteria getting inside and killing the embryo. Turkeys, ducks, and other fowl can go longer than that without their embryos being killed by bacteria.
It is always possible that the bloom is compromised and bacteria gets in. It doesn't happen often but never say never. So sniff the egg before you open it. If it smells rotten, toss it. And break it in a separate bowl before you use it or mix it with anything. That will take care of any potential embryo development. We should break our eggs in a separate bowl anyway, even if they are very fresh. We could get a blood spot or meat spot that would cause us to not want to use that egg.