I went and looked at an Arab over the summer when I was horse shopping, she had been trained for the Arab hunters and was one of the weirdest horses I have ever ridden. She was so sucked back, and held that tight little frame even when I had my hands on the buckle and was really trying to push her forward. I really loved her personality, and she was such a cute horse, I came super, super close to buying her too. However, after talking it over with my trainer and others I decided against her as I wanted her as a dressage horse and I was worred about her never getting untrained from that false frame.
I agree that that is not something I would want to encourage in a young rider, let her learn how to ride correctly and if she wants to persue that type of riding as an adult that's her choice. I love watching the dressage Arabs, they are all so stunning. I would see if you could get her interested in the Sport Horse stuff, and explain to her your concerns about showing at the hunter shows (though I think its silly for the judges to hold the breed of a horse against the rider).
RH Queen O Anywhere "Sydney"
2009 Sugarbush draft