I live in France, in most companies you don't get to finish your trial period if you are out of the office.
However for a low pay job like this one, you don't get a 3x2 mnth trial.
I was under the impression that her trial period, or the american equivalent if there's such a thing, was long since finished. If that assumption is incorrect, I agree that taking sudden unpaid leave during one's trial period is dangerous.
That being said, it's happened in my company and we most definitely didn't fire the person for that. I can see how it could happen, but I don't think it's a sure thing by any stretch of the imagination.