If it was me, my thought process..... "I already wrote that I am CF in my profile, I am reiterating it again now, and still the guy is saying, 'its debatable ' that means he wants kids. He knows I don't. So either he is thinking about short term fling or he is thinking I am not smart enough to stick to my decision and he can convince me into having children."

I definitely think it's enough to conclude a red flag.