Nothing wrong with expressing your opinion.
There is something wrong with yelling the f-bomb and flipping the bird in the face of a polite worker at a privately owned restaurant.
Speech - The US government has no Constitutional right in this case.
Disturbing the peace - Fair game for local laws and enforcement.
No one should make a Federal case of this!
She’s not being charged for flipping anyone off. She’s not being charged for being loud and obnoxious. She’s being charged for what she said!