The FEC is not a body which serves a judicial function. Your logic is the same as a police officer not enforcing a law at his or her discretion because they felt it was not a constitutional law. That is not their function. The enforcement penalties from the FEC can subsequently be appealed to the appropriate judiciary forum, where constitutionality can then be determined in the appropriate hall of gubmint. I don't think there are any enforcement agencies within the government who actually enforce anything within government anymore? Berger is the latest. Kerry's being paid while a law is on the books which specifically calls for suspension of his pay is another. It's the we need new laws thing, because they don't like the existing law or it's going to air everyones dirty laundry should it go to a test in court along with the resulting discovery process.
Washington is a disease.