A TRACON Controller reported Supervisors and Traffic Management directed an aircraft be assigned a runway contrary to the published procedures in use resulting in an 'out of control' operation and two NMACs.

Narrative

Please do a Traffic Management Review (TMR). During a very busy arrival rush Aircraft X requested XXL. During normal operations this would never be approved because the runway is full; it's not a legal operation (XXL traffic conflicts with XXR traffic); the aircraft would get to their gate (General Aviation) sooner; the complexity is too great; and it's dangerous. Please redact this: I was working Position. I advised Traffic Management (TM) and the Supervisor that approving XXL for Aircraft X is just not possible and they should deny the request and put them on XXR. In my opinion; this was extremely dangerous and it turned out to be worse than I expected. There were; at least; 2 near-misses (Aircraft Y) and two aircraft that ended up on top of each other; on the localizer; both going to XYR. The operation got so out of control that I advised the TM to 'shut off' Center so we could safely recover from the situation. They finally listened. We put Aircraft A; Aircraft B; Aircraft C; Aircraft D; Aircraft E; and several more into holding. Most of the Controllers were not told why the Aircraft X flight needed XXL. The workforce must be briefed about VIP movements that pertain to the operation. We don't need unnecessary details but; we really need to know that half of the airport will be shut down for 30 minutes. The Manager refused to listen to safety concerns. At one point they started blaming the controller who was trying to figure out how to 'wing it' during the illegal operation saying; 'well it's XXXX working and who knows what they're doing.' Another time during this one session I said 'hey; we've got two airplanes on a collision course.' The Manager replied; 'well they have a point-out.' Every time I voiced a concern it was met with some excuse that justified the danger. This is serious business.