From my understanding, there's no way to desync a controller from a PS4 without syncing it to a new PS4. When you turn off your PS4 controller, that doesn't mean it's desynced, it's just turned off. When people press the PS Home button by accident, it causes the issue of the home screen popping up. The PS4 home button seems a lot more sensitive than the PS3 button was, so when a controller is tossed in a bag or whatever, it can easily cause the home screen to pop up on whatever PS4 system it was previously synced to.
Unless there's an option to actually desync a controller and therefore have the controller synced to NO PS4 at all, this issue will be present at all tournaments where wireless PS4 pads are allowed.
Maybe I'm wrong and there is an option to desync a controller from all PS4 systems, in which case, I would like to know how to do that.