Greenwald fully explains why this was so inappropriate:
As I wrote at the time, I thought the condemnations of Rep. Joe Wilson's heckling of Barack Obama during his September health care speech were histrionic and excessive. Wilson and Obama are both political actors, it occurred in the middle of a political speech about a highly political dispute, and while the outburst was indecorous and impolite, Obama is not entitled to be treated as royalty. That was all much ado about nothing. By contrast, the behavior of Justice Alito at last night's State of the Union address -- visibly shaking his head and mouthing the words "not true" when Obama warned of the dangers of the Court's Citizens United ruling -- was a serious and substantive breach of protocol that reflects very poorly on Alito and only further undermines the credibility of the Court. It has nothing to do with etiquette and everything to do with the Court's ability to adhere to its intended function.It was a moment to be noted. It says something about traditional notions of civility and respect for institutional boundaries being diminished. It was illuminating and disappointing to see that even a Supreme Court Justice would give in to the emotion of the moment and cross a line he shouldn't. No sweeping generalizations to be made, but it's a sign of the times, that's for sure.
There's a reason that Supreme Court Justices -- along with the Joint Chiefs of Staff -- never applaud or otherwise express any reaction at a State of the Union address. It's vital -- both as a matter of perception and reality -- that those institutions remain apolitical, separate and detached from partisan wars. The Court's pronouncements on (and resolutions of) the most inflammatory and passionate political disputes retain legitimacy only if they possess a credible claim to being objectively grounded in law and the Constitution, not political considerations. The Court's credibility in this regard has -- justifiably -- declined substantially over the past decade, beginning with Bush v. Gore (where 5 conservative Justices issued a ruling ensuring the election of a Republican President), followed by countless 5-4 decisions in which conservative Justices rule in a way that promotes GOP political beliefs, while the more "liberal" Justices do to the reverse (Citizens United is but the latest example). Beyond that, the endless, deceitful sloganeering by right-wing lawyers about "judicial restraint" and "activism" -- all while the judges they most revere cavalierly violate those "principles" over and over -- exacerbates that problem further (the unnecessarily broad scope of Citizens United is the latest example of that, too, and John "balls and strikes" Roberts may be the greatest hypocrite ever to sit on the Supreme Court). All of that is destroying the ability of the judicial branch to be perceived -- and to act -- as one of the few truly apolitical and objective institutions.
Justice Alito's flamboyantly insinuating himself into a pure political event, in a highly politicized manner, will only hasten that decline. On a night when both tradition and the Court's role dictate that he sit silent and inexpressive, he instead turned himself into a partisan sideshow -- a conservative Republican judge departing from protocol to openly criticize a Democratic President -- with Republicans predictably defending him and Democrats doing the opposite. Alito is now a political (rather than judicial) hero to Republicans and a political enemy of Democrats, which is exactly the role a Supreme Court Justice should not occupy.
The Justices are seated at the very front of the chamber, and it was predictable in the extreme that the cameras would focus on them as Obama condemned their ruling. Seriously: what kind of an adult is incapable of restraining himself from visible gestures and verbal outbursts in the middle of someone's speech, no matter how strongly one disagrees -- let alone a robe-wearing Supreme Court Justice sitting in the U.S. Congress in the middle of a President's State of the Union address? Recall all of the lip-pursed worrying from The New Republic's Jeffrey Rosen and his secret, nameless friends over the so-called "judicial temperament" of Sonia Sotomayor. Alito's conduct is the precise antithesis of what "judicial temperament" is supposed to produce.