See my response to jackvalentine. If available outside of working hours was part of the implicit contract and expectations of work, the employee is being a dick. If not, the CEO was.
Why do you think an implicit employment contract is acceptable or even enforcable? There is a reason job descriptions, employment contracts and labour laws exist: to stop abuse by heavily "implied" duties. If you want someone to do some work, make that explicit.
She made it clear "outside work hours" was not contracted, that she expected it as a matter of enthusiasm and personal character - right at the time when she had ended all cause for enthusiasm, and personal character was reasonably focused on long-term survival elsewhere.
https://news.ycombinator.com/item?id=7639711