It has nothing to do with the consequences of promiscuity, it's about an obnoxious religious group discriminating against gays and singles. If you could even label all sex outside of marriage as "promiscuity", being fired from your job because your employer doesn't like sex is not a "consequence of promiscuity".
Fact is, this woman was discriminated against based on marital status. Every employee who was married enjoys a special right that employees who aren't married don't get to enjoy.
How would it be any different if I fired or didn't hire married women specifically because I was worried about them having a baby someday? Or a homosexual because I find them icky? Or a christian because I don't want them shoving their religion down my throat?