If the situation resolved in such a way that the USA had a regular majority in the Security Council, and the resolution was only rejected on the basis of a French veto, then your argument would apply.

As things stand, the US can't even get a regular majority. It seems that Iraq has a lot more brothers than you think. Moreover, many of the countries swayed to the US side did so very obviously because of economic consideration. To continue your court metaphor - the US bribed the jury. So it has even less support than the number of nations which would have voted for it if it came to a vote.