At this point it might just be easier to get a weapon that is legal in the rest of the state and if you get arrested challenge it in court all the way to SCOTUS if you have to. Odds are they would not want to actually test their insane anti constitutional laws in a real case.
I believe that he can only take possession from a NYC LGS which would not sell a non-compliant rifle to a NYC resident, And other NYS LGS will not sell to someone with a NYC address.