Especially when it would literally cost them nothing to get a lawyer to take this on contingency.
Your shallow grasp of the cost function of suing a big, madhouse employer (while you're quietly vesting, among other things) leaves pretty much the whole of human history unexplored.
Of course, if you have no supportive social network within your professional niche worth two nickles to rub together, this is an easy trap to fall into.
"Oh, the gap in my resume circa 2017? That's when I took off an entire year to sue my former employer for a HUGE punitive settlement over a toxic, offhand comment by a testosterone-fuelled, bottom-line-driven corporate executive during a late-night outing at some drunken corporate retreat."
But then, you're probably much better at explaining things than I am. After you explain it, the response would probably be, "well, son, that's exactly how we roll around here: zero tolerance. We like your spunk. Welcome on board. You start tomorrow."
Just guessing, there. IANALC, I could be wrong.
[*] I Am Not A Life Coach