It could be sexist standards. I don’t doubt they exist. But I wonder if this is more about changing standards. This woman has been in position for more than two decades, I’m sure she hasn’t just started shouting. Moser likely she used to get away with things too, but there is now less of a culture of accepting senior academics can do as they please.
There is also the factor of when you become a liability as an academic. Universities are willing to overlook a lot if you are producing world-ranking research, winning grants, or otherwise benefitting the university. If you stop performing, the administration is less likely to ignore the problems you might be causing.
In Plaut's case, she had been suspended twice in the past, and her publication record is hardly stellar (according to ResearchGate she has had 65 papers published in the 29 years, but only ten in the last ten years, of which she was lead author on only two). Meanwhile, given when she joined the department, she is probably on a very good remuneration, which may now be perceived as disproportionate to the value she is delivering to the department.
My suspicion, reading between the lines, is that Plaut won the the unfair dismissal claim because, whilst there may have been adequate grounds for dismissal, the university basically had decided that they wanted to get rid of her, and was looking for the opportunity to fast track her out of her department; this is, of course, not the correct way of dealing with staff, which does constitute unfair dismissal. But it does feel like there is a lot more going on here, which hasn't appeared in the newspapers...