EADS should have the right to bid for a contract. If the USAF did not want to have the contract bidded, they should have listed it as a “No Bid” contract. The military allows “no bid” contracts.
This contract has a strange history. After the contract was preliminary given to EADS with a US counterpart, the entire contract was rebid due to complaints from Boeing. Then Boeing was the only contractor for the new bid after the US contractor dropped out feeling that the contract could not be won. The bid should then have been closed. Instead, the bid was reopened to allow EADS to bid alone. Why did the US partner withdraw if it looks like EADS will win the contract essentially on the same grounds as 2 or 3 years ago?
The Air Force has discounted the advantages of the 767 tanker so that the A330 tanker looks superior. The 767 does not get any advantage for its lower cost and more flexibility with regards to airfields and perhaps other areas. The A330 tanker can carry more fuel but only at higher cost and less flexibility.