On the topic of what government should require from the software vendors:
I disagree with the legislation proposal, not with you. Let's require open standards, not open source. But also, let's require security, reliability and performance acceptance level even before the open standards. Ask the (proprietary or open source) software companies to deliver software that works.
On the topic of the open source software model and more specifically the GPL one:
Purchasing a softare should give you the right to sue the software vendor if this software fails to work as it is supposed. (Government requirements, quality standards and conformance tests would be a base for this to happen. :-)) If i am hurt because a car malfunctions, i can sue the car manufacturer. The same should apply to software. The thing here is - i can see the proprietary software companies as Microsoft being able to actually comply with such requirements; however, i fail to see how an open source company would be able to do it. As you said - OpenSource 'R' Us might sell me the software and might be willing to provide support (well, that's their revenue model), but i doubt they would be willing to go to the court to defend somebody else's code.
Are you personally willing to guarantee the security and the reliability of a software solution you would sell to some of your client? I assume you use gcc - would you be willing to stand by the binaries, produced by it, to the degree of taking the responsibility and allowing to be sued?