That's definitely not true, or at least in most cases. The times I've been asked that question, it was usually to test if I was committed to medicine. Like say my stats weren't good enough and the only way for me to become a doctor was through doing DO. Also another time one of my interviewer's wife was a DO. But he didn't tell me that before he asked me what I thought about the profession. I was truthful about what I thought of DO's, that there's nothing wrong with going that route, and I was accepted into that school. I suppose there can always be others that hold prejudices against DO's and if you get them as an interviewer that might change things, but ultimately just tell them what you truly, personally think.
Oh and I also said no too, but I didn't say my reason was because people looked down upon DO's.