Verizon store customer insists he is "definitely part of ISIS"

Ok wait… is it a crime to say you are part of ISIS? If so, what law would that be? The headline reads “Irwin man accused of talking about ISIS”. Will I go to jail if I talk about ISIS?
Or perhaps he was arrested for wearing a ski mask.
Did he threaten anyone?
The official charges are listed as: terroristic threats, disorderly conduct and defiant trespass.
So what was the threat, who decided what conduct was orderly and why is it a crime to act differently, and since he left the store, how can he be charged with trespass?