I assume this is going to be the new "return to line" thing. A CM will (hopefully) see the individual or group leave the line for whatever reason. Then when they return to the attraction, that CM who may or may not have seen the person or group leave the line probably has 3 options:
1) Let them into the LL
2) Walk them to a spot further up in the standby line (if the queue allows this) hopefully to meet up with family
3) Say sorry and show them the back of the standby line
If that decision is being left to the attraction cast member, I pity them and also feel like the LL abuse will get even worse.