I think the "rude and threatening language" while over the top is a minor issue and she should not have been fired for that.
Just a thought:
'Sticks and Stones' is an English-language children's rhyme. The rhyme is used as a defense against name-calling and verbal bullying, intended to increase resiliency, avoid physical retaliation, and/or to remain calm and indifferent. The full rhyme is usually a variant of:
Sticks and stones may break my bones But words shall never hurt me.