Buy Whisky at Airport Duty Free Shop?

In 2004 I was buying Japanese whisky at the airport duty free shop to bring back to the U.S., but was declined when I told them I was getting on a U.S. airline (United). Is this still the case? Is it considered part of my carry-on and thus against TSA regs?

I really don't understand this, the ban on liquids was not introduced until 2006 and Duty Free would be exempt anyway as it is usually purchased air-side.

What I would say is that I believe that there is not too much of a difference between the price paid in liquor stores and that paid at "Duty Free" stores at the airport in Japan. So just buy your bottle in a regular store and pack it carefully in your checked luggage. If you go to a good department store or somewhere like Tanakaya in Tokyo (Mejiro 3-4-14, on Mejiro-dori just a few seconds west of Mejiro station. Open 11am-8pm. Closed Sundays.) you will probably find a wider and better choice than at the airport anyway.

I didn't understand it either.  I had already passed through the security check and had assumed that any liquor that I bought would be all right since I wouldn't have access to it until just before landing. Before boardIng the plane I was also told to drink or dump a plastic bottle of water that I had bought after clearing security. But this incident was back in 2004. I just want to know if this has loosened up. 

I am not as concerned about the duty-free aspect of buying the whisky, as I am about packing it.  United currently has a bulky policy regarding alcoholic beverages in checked bags:  

"When placed in checked baggage, glass bottles must be in a Styrofoam-type insert that is molded to the shape of the bottle and completely encloses the bottle."
http://www.united.com/page/article/0,6867,52062,00.html

Can't comment on 2004 but your problem may be more of an issue when getting to the States if you have to change to a domestic connection; it will not get through the liquids security then.
If you are deplaning in the USA and not flying on elsewhere then it shouldn't be a problem.
However I also agree the Duty Free saving at the airport isn't great, if at all:however I understand the packaging issues.