I'm just grateful you ignored my prolific typos.
But seriously, we're all philosophers here, so let's make a distinction! Aren't there really two different types of "front" language? The first might be termed purely symbolic. The mekong delta, Carter's sweaters, or better yet, Regan's gestures towards being pro-life that kept that group on the reservation. These have the property that the metalanguage argument defeats itself if stated in the object language. Example: You can't just come out and say "here's a transparent political sop to the pro-life wing that doesn't really do anything" in the object language. Doing so would defeat the purpose of the utterance.
Other front language is different, and we might call it 'tactical.' These are a case where the true reasons are merely undiplomatic or radical. Generically, no president would say "we need to do this now because we'll lack the political will to do it later." It simply isn't prudent to diagnose the country with ADD. To take an example closer to home, no policy will likely be justified publically as follows: No president could ever justify a policy with "because Saudi Arabia, while an ally, is one half crazy, one half corrupt, and all the way unstable, so we need another option."
Isould argue the Bush adminsitration's use of front language largely falls into the first category. You go with "WMD" and violating UN orders because you care about nuclear weapons and larger geostrategic points. This division helps to explain why Bush gets more of a pass than Kerry. As a way of reverse proof, I think it is precisely those who believe Bush employs the first type of front language (rendering the true statement of war aims: "I want to gin up a crisis to be popular") who don't give him a pass, and are indeed unhinged by the prospect of Four More Years.
It is only legitimate to raise the question of ulterior motives when the nominal, proffered rationale is too preposterous to entertain. Neither of Kerry's votes referenced above (Vietnam-themed stump speeches are a different subject entirely) is in even the remotest danger of failing that test.
Kerry said he voted to authorize force because he didn't want to tie the President's hands as he pressured Saddam to comply with the UN's demands. This is neither a cause for suspicion in itself, nor in conflict with later criticizing the conduct of the war.
As for the $87 billion: Kerry voted for one bill for that amount and against another. Bush promised to sign one bill for that amount and threatened to veto the other. To regard the positions as anything other than equivalent is to endorse the premise of an imperial presidency.