The person she told that to, Homer Hickam, had no say in the firing, expressed disappointment after, and helped her get another job after (though I do not recall if it was successful). In an era where companies are increasingly sensitive about what employees post online, she had it much much better than just about anyone else in the world fired for the same thing at least.
And really… perhaps I’m old fashioned, but posting stuff like that in the same tweet as your NASA offer was pretty poorly thought out. NASA doesn’t feel like the type of organization that wants its employees associated with messaging like that.