Update: A comment from a spokeswoman for the attorney general's office was added to the second-to-last paragraph.SPRINGFIELD — Near the end of its decision to reject Paminder S. Parmar’s try at a $560,000 estate tax refund, the state’s top court wrote the man may have missed his opportunity earlier.His claims against the state’s treasurer and attorney general for enforcing what he argued was an unconstitutional estate tax law were dismissed under a rule that prevents the state and its officials …