Yes this is a cockerel. You don't see any wattles because pea comb and beard. The most probable explanation as to why he stopped crowing is because the other one has, and is the top male. I haven't found this to follow them through into adulthood, but younger cockerel *sometimes* suppress their crowing when another male higher in ranking is present. Usually that bird is also older, but it seems like in your case this guy took it too seriously. Or it might be that he wasn't up for it yet. I've had cockerels who tested out their crows, stopped, and then started crowing for good a month later