I don't know that he is more aggressive than the others. It is quite a show when 8 chicks and 16 hens all come racing out of the coop in the morning. They all dive for the BOSS and whatever kitchen scraps are out for them.
Ordered pullets and yep they to make mistakes. Got a Barnevelder cockerel 2 years ago. Meyer guarantees 90% so I'll get my money back since I ordered 9 chicks. Unfortunately the money is all you get back, the unwanted roo/one less layer is on the buyer.
I don't expect to see any rooster feathers for some time. Trouble (the Barnevelder roo) was CLEARLY a roo at 3 weeks. But you have to wait until they are at least 11 weeks to claim the error. Similar to this one, Trouble had no back or shoulder feathers when all the girls, including Trill (the other Barnevelder) were pretty much feathered out and his tail, like this one, was only a stub for quite a while.