KBS made assurances to JYJ that they would not cancel the scheduled New 7 Wonders concert appearance on July 20th. That's what Prain Director Lee Jae Eun revealed in an interview with Radio 21 about the whole KBS/Jeju/N7W controversy that's still churning among JYJ fans from around the world.
Prain is the company which handles JYJ's communication with the media.
Because JYJ has had to deal with so many cancellations due to powerful external pressures, they didn't accept the job unless KBS made assurances that the broadcast company wouldn't up and cancel.