I am assuming that America went and helped take out Germany and only after that was won/in the process of being won, then moved their fleets into the Pacific to clean up there.
But because 20 turns ago (or whatever) Japan sent 2 bombers against W. USA for an SBR and managed to get 10+ (not unthinkable) they have a permanent VC that cannot be liberated for the rest of the game.
In other words, I think it is a little too powerful. Perhaps if the W. USA VC was liberated if Hawaii, Australia and E. Indies or Borneo were in allied hands just to give America a chance to liberate W. USA it would be slightly less, for lack of a better term, “broken”.
Although, honestly, I’d say if you wanted this rule, the best option (in my opinion) would be that the VC counts in the Axis total until Russia’s next turn. This way it automatically gets liberated by America but can’t be used in the allied totals for a VC victory if it takes 10 IPC in damage that turn. At least this ties up Japanese resources in maintaining it, can be used as a last ditch effort to stave off a VC win but does not make an unrealistic scenario where America just cannot ever liberate.
The next big issue is, under your ruleset as I read it, Japan sends 2 bombers into W. USA, gets 10 IPC and then can retreat those bombers to go do something else. Since America cannot liberate W. USA, this is a VC they don’t have to defend or attack or even concentrate on. If you had to conquer it, you would routinely have to reinforce or invade it to keep it under your control.