donrae- glad you asked! the real reason BR as father not likely is because they are pure for the E(black) gene. It's 'very dominant'. Let's say you take out the barring out of him, he would be a solid black chicken. This rooster over any of those hens would still produce 100% half E birds- hatch out with black down(but also in this hypothecial case, any barred chicks would be male.. however they still would start out black/white).
Another example of E dominance over other colors is black sex links, a lot of them are RIR roo over BR hens. So far all BSL roosters I;ve seen were barred with white in the pyle areas, indicating BR are possibly mainly or all silver based.. another reason to doubt the BR being father of this cockerel- he's not silvery or "golden". BSL hens get their brown from their RIR fathers being pure for gold(silver is sex linked).
Going back to pure BR father plus if they are really silver, then all of the chicks would be barred, all pullets would be black/white- even if they leak, it would be white, no gold. Only some cockerels would manage to show some gold coloring when they get their rooster feathers but even so, it would be mostly confined to pyle zones(that's why I say 'start out b/w' or start out with black down).
Now, if the BR was really a BSL, there would be a chance of him being the father because BSL roos out of RIR and BR would be half silver half gold, meaning they can throw offspring with gold coloring... and also because BSL are not pure for E- they have the Wheaten gene from their RIR father, they can throw chicks that are not black with say, a rainbow(which are very likely wheaten based) or buff brahma or.....
leg color- his legs look white which would rule out BR or BSL bred with brahma as yellow leg/skin is recessive. Have to have at least one white legged/skinned parent.
Comets IIRC are cross with of a white bird with production reds, so they are not pure for dominant white, so half of their offspring would get white the other half not(if bred to a bird lacking dominant white).
If that game rooster is not crele but has white or slate legs and pea comb, I'd be very tempted to guess it's him and the rainbow hen.
Hope this is clearer than mud.