By their actions, Zygna also signaled to the other employees that Zynga was going play a "heads we win, tail you lose" in the future. Who in their right mind would ever work for that founder again?

Going in, a startup employee gets some stock (upside) in exchange for risk (downside). Zygna used their relative power to reneged on that agreement to capture the employee's upside. "You can give us your money or we can take it AND fire you. Hey, but its your choice."

They were in no way being nice.