Nah, being to big to fail doesn't violate anti-trust laws, but just try NOT stealing students from other piano teachers.
The association's sin, according to the feds, rested in its code of ethics. The code lays out ideals for members to follow—a commitment to students, colleagues, society. Tucked into this worthy document was a provision calling on teachers to respect their colleagues' studios, and not actively recruit students from other teachers.