Now what about an Open Source OS. NSA and DoD loves them some RHEL (Redhat Enterprise Linux). Would they pay RHEL enough to produce binaries that have backdoors in them? Yeah, CentOS compiles the sources and that's cool. But most organizations buy RHEL for support.
Well I would say they would be very stupid to do that as if it ever comes out it will immediately destroy their product.
Now, just like PRISM will most likely damage US companies using or offering cloud services, any revelation of an exploit that _could_ have been developed with cooperation form manufacturer would destroy that company's business.