It's absolutely rediculuous. It even sounds like she wants to learn; schools don't get that often so they shouldn't tell her to go home. Also, the Zero Tolerance policy is gay. Shouldn't exist.
This is typical treatment of special ed kids in public schools. I could tell you many stories, but the first one that comes to mind is that my daughter had to share a locker with another girl that she didn't know. As a matter of fact neither ever saw the other and for several months had no idea who they were sharing the locker with. When the girl found out that her locker partner was in special ed, she threw out my daughter's coat and books and invited three other girls to share the locker. My daughter reported it to the vice principal, who answered that those girls wouldn't do anything like that, they're very popular.
OMG you're in trouble now, you used the G word, to the principles office with you :)