Boeing is just ticked off that they've finally whipped it out and stomped on it so hard that the USAF told 'em to "sod off".
The A-330 is such a superior aircraft to the 767 that it's not even funny. The 767 production schedule is far slower than the A-330 which would put delivery of their version well behind the A-330. The A-330 is also a substantially larger aircraft, which besides giving it larger offload capabilities, (245,000 lbs max fuel capacity vs the 767's max fuel capacity of 160,660 lbs), also gives it a longer maximum operating range, and the added ability, and this is huge, of AF refueling Wings to be able to "self deploy" with only their tanker aircraft instead of having to tie up C-5A's and C-141's in order for the units to be able to "forward deploy". Simply put, if the USAF is permitted to buy the A-330's, over the long run, they will be far more cost effective to operate, both for the actual aircraft, as well as for the cost to the units operating them. Another added advantage of the A-330, due to it's size, is that when tankers are used in "non-traditional" roles, the A-330 will be able to perform the duties of 2 or more of the 767's for a substantial cost savings.
Simply put, there's no comparison between the aircraft, and the A-330 is a hands down "no brainer" for the USAF.