As far as negatives for the Supreme Court go, it's hard to beat the appointment of George W. Bush as President. Allowing unlimited money into political races (Citizens United) comes in a close second. Compared to these, having the Court's right wing not attend the SOU Address is barely a blip on the wingnut radar.
Maybe Scalia will go hunting with Dick Cheney instead... And Alito can stay home and mouth off to the television.
"“If things devolve to where it looks like an implicit indication of support or non-support for whoever the current president may be, that’s a big negative for the court.”"
- Roberts Decision on Attending Obama `Pep Rally' to Send Message - Bloomberg (view on Google Sidewiki)