They didn't like the viewpoint she expressed, didn't like the criticisms she raised, so they blocked her (well her and 7 co-author's) paper. When she said that was unacceptable and stood her ground, they badmouthed her and fired her.
You don't have to agree with the paper's criticisms (and it appears they were just part of a longer paper) to be concerned by viewpoint censorship. If the paper wasn't worthwhile or based on facts, then that would have come out in academic review, either in peer review in the paper, or in subsequent papers rebutting it, or pointing to subsequent changes. That's how academic inquiry works.
But if companies can silence ethics researchers who express concerns, whose job, as AI ethicists, is to express concerns, that fundamentally undermines academic inquiry into the topics at hand.