Rooster who thinks he is a Hen

Yesterday I cleaned out on of my old smelly nest boxes, which was disgusting. But I got it super clean so the hens would lay in it. I put in newspaper, than pine shavings, then nice hay. It is a wooden 3 hole nest box. I put it in my dairy goat barn which is also the home to 7 of my 50 chickens. The chickens include 2 silver laced wyandotte roos, 2 cochin hens, 1 wyandotte hen, 1 white her, and one 3 year old blue leghorn hen. I was in the barn today with my beloved goaties and I looked in the nest box. One hole was empty, the leghorn was in one, and there was something in the other but it wasn't one of my hens. So I got closer, and behold, one of my wyandotte roos! He was in a laying position, was growling like a hen, and was arranging hay in a nest! I am absoultly sure this is a roo, he crows, chases the hens, has a huge comb and waddles, and looks nothing like my wyandotte hen, plus he kicked me yesterday. Is this normal behavior? I have had chickens over 4 years and have never seen a roo in a nest box.