IMHO, Part of the problem we're seeing is a result of the consolidation of our defense industries. I'm not sure allowing Boeing to buy MD was such a good idea. Both Northrop and Lockheed are capable of building a tanker, and Lockheed actually has some experience there, while Northrop's larger aircraft have been limited. Of course Northrop never really had a viable commercial offering, and Grumman's larger aircraft are not large enough. Leaving just Lockheed with any experience with large commercial airframes that lend themselves to this application.
I'm all for competition, but I'm also for keeping large strategic assets "in-house" so to speak, and one of the reasons for that line of thought is that which you mentioned.
As for McCain, yea, he may have an ax to grind with Boeing, and Boeing (former MD execs IIRC) along with people in the Airforce, were responsible for that debacle. People are in jail, heavy fines have been paid, and Boeing's CEO at the time resigned in disgrace.
And there's the so far alluded to changes in the RFP for various reasons. A whisper here, a whisper there, money talks, and future funding requests for other (AF) projects can be put in doubt if certain political games are not played. Some here have expressed doubts about such things, but there is actually a lot of precedent for it when Billion dollar contracts are at stake.
The whole thing smells.