You are making a solution based on one specific scenario. You cannot do that when you are looking at the general problem as a whole. If you scenario, other people would be transported to the other players. They then can have complaints about shards bouncing, which in general is a bad thing.
Do I have a solution? It would be a general solution. Let the user decided. Have virtual servers that shows the current balance of the PvP ratio and they can choose which one to join and be transport to those servers.