Yeah, you would.
Erhm... huh?
So I guess what you're saying is that the UN didn't do the job of enforcing its rules so the US stepped in to enforce its rules for them.
For one thing, the US and everybody else would be a hell of a lot better off right now if, when it came to Iraq, the US didn't jump in and start enforcing the UN's rules against the UN's wishes. Okay? That much we now know.
For another, Powel stood up in front of them with a PowerPoint presentation the cost of which probably equaled the GDP of a few third world countries combined, trying to show the UN what it thought it knew. It's not as if Uganda or wherever has spy satellites.
When push came to shove, the US kicked out the UN's ability to verify the intelligence that the US was so kindly supplying to them. The UN wanted to check it out. The US wouldn't let them. And you wanna foist the blame on the UN?
Your remark seems only to say "They wouldn't do it, so we had to."
Thus, in light of everything we now know, your argument becomes "They wouldn't do it, because it was not justified, but we did it anyways, because they wouldn't." Well good for you. It's irrational.