Okay, then I see how it was easy for the trooper to make that mistake. When one clicks through from one field to the next the default that comes up for the state of registration is "NY" - he just clicked the "next" button one too many times without realizing it. I do that all the time but always catch it and go back. We get so used to writing NY cars that our muscle memory takes over (so to speak).
Again, this will not get the ticket dismissed, especially if the plate is otherwise correct. If you want to fight it you'll have to go through the system and it will require a personal appearance in court at some point.