I agree with Mugsy. It sounds like your trainer is breedist, or at least prejudiced against pits. No one with a brain in use would take an owner aside, at a first class, and give them a warning like that.

The behavior toward other the puppies sounds to me like Buddha is a natural alpha. If you've never seen a litter of puppies interact, or pups in a kennel setting, it can be confusing. But some pups are naturally the leaders, just like some kids. They have to be king of the mountain or there's hell to pay. Others just go with the flow, and still others tend to be submissive. Alphas tend to be smarter, too, and so you'll have Buddha's rapid progress to crow about.

You're smart to want to give him the most training you can, especially since you've seen the result of not doing that for Riely. But pit bulls aren't naturally hateful toward all other dogs, and Buddha will be just as protective towards Riely as to you, as he grows up.

Mac