"...the department leadership concluded that the debate over both his views on diversity, equity, and inclusion and manner of presenting them were overshadowing the purpose and spirit of the Carlson Lecture"

"The Carlson Lecture is not a standard scientific talk for fellow scientists. It is an outreach event, open to the public, with a speaker who is an outstanding scientist and role model [...] to inspire young people to consider careers in STEM."

Seems fairly reasonable to me that you wouldn't want someone with divisive views on diversity giving your outreach lecture.