Hello, welcome to pettalk! I am sorry to hear that! I'd find another behaviorlist! No matter what the breed is, I think aggression is unacceptable. That person doesn't know what they are talking about; Rotts are great dogs!

I sort of had a similar thing happen the other day. I called the shelter because I had caught a pitbull that had been obviously fought. The officer said "That's just how pits are. Send him back home."