Imagine saying something controversial on social media and having that plastered all over the web.
Unless your business is media or heavily linked to public perception, your controversial opinions should be irrelevant to work. This is different to a worker who doesn’t do their work and sues, that is _very_ relevant to future work.
Your premise is also incorrect: there are businesses that are happy to take on extra risk and will happily employ felons or other black sheep. Many people are willing to give a second chance, but they should be aware that they are giving a second chance.
That is, unfortunately (or fortunately if you're that kind of person), not how things work for a large amount of jobs. If you have that scarlet letter, you're shut out of a lot of positions, even when that history _shouldn't_ matter.
Instead of taking responsibility for it, she played the victim card and filed a lawsuit in bad faith. She does not belong in any workplace.
To be employed by them, for so long, means that she was likely productive for most of her time there (then slacked off at some point) and/or how employees are managed and evaluated at that company is completely dysfunctional.