[boodm]

What stops the NSA from buying the tools?

[jlgaddis]

Nothing?

We don't know that they didn't buy (some of) these particular exploits (in the recent "dump") and, in fact, it's very likely that they do buy exploits. I imagine that CNE of high-value targets is an area where they could "never have enough".

[lern_too_spel]

These tools are years old. They can just report these vulnerabilities to the vendors and use their new exploits.