The Boston Globe has published TSA statements declaring that those arriving without a MASSACHUSETTS LTC will be arrested. Unfortunately, MA does not recognize any other state's Licenses, so you are not legal to carry a handgun here--boxed and locked or not. Arriving in Boston's Logan Airport does not meet the "traveling through" clause of the Federal "Safe Passage Act".
As mentioned, the safest way is to transfer FFL to FFL.
One other option, providing your son has a LTC-A, is to have him bring the gun in state himself the next time he visits you.
Or, fly to a nearby gun friendlier state and have him pick you up there and transport the gun into MA under his own license. As mentioned, make sure you don't bring any normal capacity magazines (more than 10 rounds unless grandfathered and you have receipt), and no modern sporting rifles with collapsible stocks.
Another option, just because I'm thinking creatively. I would not try this without a signed letter from a lawyer AND from the Boston Chief of Police or TSA authority. You are legal to declare the handgun in KS. Your son, assuming he has a LTC-A is legal to retrieve it in Boston. You could pursue the course where you check the luggage and your son retrieves it so it is never in your possession in Boston. Although I think the point of breaking the law and arrest is in retrieving the luggage with a firearm, I would NOT try this without getting the above mentioned documentation.