The idea is actually good , but not in all cases , as for CEs and ARs , cops already crack the heck out of them , they the entrance of CEs and wait for cops to spawn out of the event , and in ARs a lot of groups gather and crack them most of the time.
The only case this would be helpful and fair is when a riot is going on , so I think this idea would only be good if there was a restriction to only allow its usage only when there there's a current riot placed by a CB.
EDIT : And also add a limited distance from the riot point so no one can abuse it near CEs and ARs while a riot is going on.