My rooster,(OEGB) will stand near the hen as she in the nest laying. He watches and makes gurgling, cooing noises as she struggles and sings her egg song. Once the egg is in the nest, Roo gives the most triumphant crowing ever! Then he'll do the gurgling & cooing, pick up some treat & feed the hen. ~ what a guy!
Our OEGB's do that also. They will even get in the nest before the girls to make it all nice for them. We have a few large breed roos that also do the same thing.
My buff orp roo will do the guarding thing too! That is usually how I find a hidden egg-laying spot, I stalk my roo. When I see him just standing near an odd spot it is usually because there is a hen hidden somewere near him laying an egg