Id be happy for Newsnight, or Panorama, to run such a debate in controlled conditions, where the background of any participants can be vetted, and where the Panel is very experienced with the right scientific/medical credentials are given proper time to respond. QT is not the right place and format.
When people say that freedom of speech is paramount- how far would you go. Would you accept it if FB invited people on the next venue to explain why they think it is valid to be antisemitic, or to cure cancer with prayers and homeopathy, or whether it is fine for MPs to dismissed for being too Muslim, er .... There must be limits to the air given to extreme views- especially when participants are not vetted properly, and the Panel not given time to respond properly, with evidence.