Texting does affect other students.
Her job is to enforce the schools policies and procedures, including but not limited to enforcement of cell phone policies. The teacher called the SRO when she was unable, thus following proper policies. Teaching is just a componet of what teachers actually do.
The fact that the disruptive student was removed from class makes the class more manageable. It's not lose-lose for the teacher, it's actually a net gain. By not paying attention, the student demonstrated that paying attention in class was not a priority.
Students do not laugh, giggle, or otherwise make a scene while taking notes. If the student was causing a disruption during notetaking, then they should be removed from class as well.