Libel maybe; people can and have gotten fired over CoC violation allegations (warranted or not) and the consequent internet witch hunt; a famous case is "Donglegate".
There's a dangerous trend where an accusation alone is enough to have people lose their jobs.
Libel would require the allegations be, at the very least, false, and not an opinion. It appears all factual allegations here are true (he presented the talk, he used bits from another talk, he called a speaker wrong), and everything else is an opinion based on those facts. So it's not libel.
And any improper employment termination suit would be against the employer, not a conference organizer, because in a very direct sense, it's your employer that chooses whether to fire you or not.
That's was really nothing to do with a CoC violation directly though. It had to do with a social media blowup that embarrassed and inconvenienced companies in a way that made it easier for both companies to just fire the individuals involved. (As will tend to happen unless an individual has a lot of power.)
From the article, the alleged harassment was two phone calls and a zoom call, all of which the recipient answered and participated in. That's not harassment.
There are legal expectations for how companies can terminate employees, I think it's only fair that professional organizations organizing professional events also be held legally accountable for the impacts they have on individuals.
More often than not, these responsibilities emerge after onerous legal discourse, legal judgement, and promise of punishment.
You may think it’s fair, but you don’t have a (in the US at least) constitutional right to be protected from inexperienced application of a code of conduct.
> constitutional right to be protected from inexperienced application of a code of conduct.
I'm not sure what the constitution have to do with it? Inevitably, all it takes is a few court rulings in favor of defendants claiming that CoC enforcements have caused harm.
