DMF,
I think you missed something in Charon's post there. He was not dissing the flag at all. What he was saying is that the constitution and the BoR are the thing that the country is formed upon, not the flag. If you remove the constitution and the rights we are guaranteed because of it, we are no longer the nation that was started 200+ years ago, we would be another banana republic. We would not have the right to claim a symbol of freedom in that situation.
His statement about the oath of office is the same as it is for the President on down. You do not swear to uphold and defend the flag, you swear to uphold and defend the constitution. The constitution is the basis of the government not the cloth waving above the building.