Gagging?

Does the rabbi know Professor Toaf’s book on the blood libels? I am attaching a link.
https://www.ynet.co.il/articles/0,7340,L-3365294,00.html
In such a case, is it right to silence a person without even examining his words objectively?
This is a professor who claims there is evidence that at least one sect in 15th-century Italy murdered Christian children for religious purposes.