CERN did not cut ties because some other scientists rebutted his claims. This was completely ideologically driven. Strumia was presenting on a gender workshop and his crime was to be counter-narrative. Check for yourself:
https://drive.google.com/file/d/1c_NyUhOZ8erdqU2AGZJZtNfFeA9...
And if you have any question as to CERN's motivation, here is their official statement:
Updated on 1 October 2018
From 26 to 28 September, CERN hosted the first workshop on High Energy Theory and Gender focusing on recent developments in theoretical high-energy physics and cosmology, and discussed issues of gender and equal opportunities in the field.
It is unfortunate that one of the 38 sessions, by a scientist from one of the collaborating universities, risks overshadowing the important message and achievements of the event.
CERN, like many members of the community, considers that the presentation, with its attacks on individuals, was unacceptable in any professional context and was contrary to the CERN Code of Conduct. It, therefore, decided to remove the slides from the online repository.
On Monday, 1 October, CERN suspended the scientist from any activity at CERN with immediate effect, pending investigation into last week’s event.
CERN is a culturally diverse organisation bringing together people of many different nationalities. It is a place where everyone is welcome, and all have the same opportunities, regardless of ethnicity, beliefs, gender or sexual orientation. Indeed, diversity is one of the core values underpinning our Code of Conduct and the Organization is fully committed to promoting diversity and equality at all levels.
CERN always strives to carry out its scientific mission in a peaceful and inclusive environment.