I’m not a lawyer so I could be completely wrong on this, but Holder’s contempt of Congress is ongoing. It is not a one time action in the past, but is continuing at this moment. Consequently any law that prohibits paying a government official who is in contempt of Congress would apply to Holder because his contempt is ongoing. Even if it were not ongoing, Congress could surely find him in contempt for any number of wrongdoings after the law is passed.
I too am CONTEMPTUOUS of Congress! LOL