I'm curious how this "statutory duty to freedom of speech" works, considering this is someone spewing racist pseudoscience (if it even reaches the level of pseudoscience). They've also been suspended from academic institutions multiple times. And "may" have caused the suicide of another academic.

Even ignoring the duty of care to students and the "inclusive, welcoming environment" commitment they allege they have... What value is there in debating obviously wrong ideas?

If some professor firmly believed gravity isn't real and the Earth is flat, would that be worth hearing out in an academic context? What value is that to students? "Here's how you debate someone with ingrained ignorance/stupidity"? There are plenty of other ways to do that - use recordings, role play, go out to a (free) event of theirs.

And I've even charitably assumed this is an event where some debate will take place...