Don't you think that what you mentioned is not the only possible senario? I mean what about cops camping there doig nothing and waiting for the ces to finish just to have random kills / arrests, what about the wanted criminals who arrives to the ce location and could not join for whatever reason, so they can't fight back the cops who came to kill and arrest them? , this won't really help in my opinion and may only ends up with cops having advantage over the criminals,Correct me if I am wrong but I remember long time ago, cops could be able to join the ce from a interior located in LSPD, so why don't we add this back and the problem surely will be solved.
I think it's smart idea so criminals will stop attacking cops outside CE while waiting