Their lawyer, Ben White, said that the T-shirt did not appear to violate any school policy.
"I just don't understand why this teacher reacted the way he did," said White, who said he asked school officials to preserve surveillance video of the cafeteria.
White said he planned to meet Monday with Principal Ernestine Sutherland.
A message left Sunday at a phone listing for an Ernestine Sutherland in Logan wasn't immediately returned.
White said schools can place restrictions on students to prevent disruptions, but can't take away their First Amendment right to free speech.
"If a teacher is telling you to do something that's wrong, I don't think you should follow it. But I also don't think you need to do it in a disrespectful way," he said, adding that he does not think Marcum was disrespectful.
White said he also wants to get the criminal charges dropped.