Accidentally engaging in an argument with a minor

If a child, 12 years old, were to instigate a conflict with an adult, and that adult engaged in the conflict without any knowledge that they were a child (no indication on the social media account), what could potentially happen if they pressed charges? The child committed far worse crimes (threats of murder and violence on an entire family) and the adult only mocked them and insulted them repeatedly. Is the adult responsible for not finding out the aggressors age beforehand? No threats were made by the adult but very unkind things were said.