Total overreach, and I don't understand why they couldn't have gone with some simpler "destruction of evidence" charge (which I'm sure is still fairly serious and would turn a fine into a prison sentence).
Because previous laws aren't applicable to this situation. To my knowledge, and according to the two surveys of federal obstruction of justice statutes, all previous laws (like 18 U.S.C. 1503 and 1505) only apply when there is judicial or grand jury proceeding at the time. The purpose of 18 U.S.C. 1512(c) and 1519 (enacted by Sarbanes-Oxley) were to expand the scope of obstruction laws to apply when an investigation was underway but charges had not yet been filed. That is what the prosecutor means when saying the intent of these sections was to close a loophole or fill gaps in the current law. I have to agree that it needed to be filled, and this was the correct statute to apple to this case.
In both the new and old statutes cases the offender must be aware of the proceedings or investigation and act with intent in order for the law to apply, so they can't be abused in that manner. Sarbanes-Oxley also doubled the maximum penalties for these laws, which increases the potential for abuse. Personally, I would feel better if the statutes explicitly stated that the maximum penalty should be proportional to the penalty of the crime being covered up. That is currently up to judicial discretion and precedence, AFAIK.