The "contract" in TARP stipulates that Treasury purchase mortgage-back assets from financial institution in exchange for non-voting shares of the institution.
So not only salary are negotiated between company and management, two private parties, Treasury still do not have the right to "condition benefits on the nonassertion of rights".
Also, because the power to delegate TARP money was given to Treasury, something Napolitano also considered unconstitutional, and that the plan to cap executive salaries belongs to Obama, not Congress, Congress will have no role in setting these conditions.
So not only Congress do not have the right to make these stipulations, they're not even the ones doing the stipulating.