I think the problem I have with the order is the "or to pose a significant risk of committing" language. If this were explicated by a statistical process they intend to use, that'd be one thing. As it stands, it could be a significant risk to let a democratic congressman vote against funding. That could be interpreted to threaten stability. Not likely, but possible.
The problem with the possibles is that Bush, like a number of other presidents, is trying to strengthen the Executive branch to the exclusion of the other branches as much as possible. It's been done, it's been undone; people have varying views on how important it is for the country to have strong executive vs. legislative vs. judicial branches.
I personally find the idea of the branch that consolidates the maximum amount of power into the hands of the fewest people to be an undemocratic impulse. I firmly believe that politics should be effected by politicians -- people who have training for government -- as opposed to putting any random decision to a total popular vote, but I do think that John Stuart Mill was right when he suggested that the way to reach a good decision is to have voices in conflict work towards a solution.
When historians look at the war in Iraq, what will they compare it to? Vietnam seems far and away the most likely analogue to me. What good will they say is to come of it? Democracy cannot be forced on a people. It is antithetical to itself. If "nationbuilding" consists of putting those people in power who are sympathetic to democracy, then it is merely tyranny from outside. The power depends on the support of overwhelming external force, so it cannot be democratically elected. Ironically, the will of the local population in these cases seems to be NOT to have the installed sympathizers to democracy. This is cultural imperialism, and we have the guns.
I don't know if US foreign policy has an ethical choice any longer: leaving will generate a power vacuum that will definitely have damaging consequences, and staying is just shoring up that vacuum for a more dramatic fall when we lose interest as a nation. We are not the rightful arbiters of the Iraqi government.