We've seen examples of these sorts of sieges done before, and without fail they rely on some admin fiat (or literally "no you can't break in until we say so") to function. That's just how it is, unless you slap both sides together in a white room and hope one side doesn't get exceedingly mad (which they do anyway).
No matter how well cops fortified the place (actually, because they had foritified the place) you'd probably be seen a lot more complaints had the siege been deadstopped on the lower levels, with claims it was an impossible doomfort (by design). Have rebels use their cool tech stuff to break in and, as happened, it'd be called into question and complained about.
This style of event was, no offence, a lose-lose for the event organizers and players. Even C24 was heavily complained about at the time, primarily because whenever rebels broke through they'd be met with a strider or something else to make them fuck off, but it was a neccesity so they couldn't bulldoze their way through and win the map. A Red Letter Day worked only because rebels were told to hold off attacking until the final day and the goal was always to get them inside the citadel.
tl;dr: Siege style events never work especially well, they're a mess to organize and one side always feels fucked. You literally cannot plan for which side kills which better and even if you do, it usually seems like bullshit from the other end.