Chef's folly:

What about stabbing him as a fair payback?

You know, fucking is such a painful, dreadful experience for women that I really think he got off easily.
She should have chopped off his balls and made him eat them, after being so terribly traumatized by a guy asking her to fuck not once but twice!!!

It's up to both of them to act like intelligent people.

As far as this specific situation goes, she explains that he came onto her twice; she refused twice. In retaliation, he ignored her and her work, which would have been detrimental to her career:

Because he would not be advancing her culinary education with his attention and advice.
Because it might incite the others to treat her badly too, and isolate her within the team.
Because if she quit in response to this treatment, he might take it upon himself to write a negative review to a future employer, thus further damaging her future.

Because there is a general understanding about relationships in the workplace, which this incident violated.